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| <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0> | |
| <tr><td> <font size=+3 color="#EEEEFF" face="Georgia,Palatino,Times,Roman"><b>CommandLine 2.0 Library Manual</b></font></td> | |
| </tr></table> | |
| <ol> | |
| <li><a href="#introduction">Introduction</a> | |
| <li><a href="#quickstart">Quick Start Guide</a> | |
| <ol> | |
| <li><a href="#bool">Boolean Arguments</a> | |
| <li><a href="#alias">Argument Aliases</a> | |
| <li><a href="#onealternative">Selecting an alternative from a | |
| set of possibilities</a> | |
| <li><a href="#namedalternatives">Named alternatives</a> | |
| <li><a href="#list">Parsing a list of options</a> | |
| <li><a href="#description">Adding freeform text to help output</a> | |
| </ol> | |
| <li><a href="#referenceguide">Reference Guide</a> | |
| <ol> | |
| <li><a href="#positional">Positional Arguments</a> | |
| <ul> | |
| <li><a href="#--">Specifying positional options with hyphens</a> | |
| <li><a href="#cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> | |
| modifier</a> | |
| </ul> | |
| <li><a href="#storage">Internal vs External Storage</a> | |
| <li><a href="#attributes">Option Attributes</a> | |
| <li><a href="#modifiers">Option Modifiers</a> | |
| <ul> | |
| <li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a> | |
| <li><a href="#numoccurances">Controlling the number of occurances | |
| required and allowed</a> | |
| <li><a href="#valrequired">Controlling whether or not a value must be | |
| specified</a> | |
| <li><a href="#formatting">Controlling other formatting options</a> | |
| <li><a href="#misc">Miscellaneous option modifiers</a> | |
| </ul> | |
| <li><a href="#toplevel">Top-Level Classes and Functions</a> | |
| <ul> | |
| <li><a href="#cl::ParseCommandLineOptions">The | |
| <tt>cl::ParseCommandLineOptions</tt> function</a> | |
| <li><a href="#cl::ParseEnvironmentOptions">The | |
| <tt>cl::ParseEnvironmentOptions</tt> function</a> | |
| <li><a href="#cl::opt">The <tt>cl::opt</tt> class</a> | |
| <li><a href="#cl::list">The <tt>cl::list</tt> class</a> | |
| <li><a href="#cl::alias">The <tt>cl::alias</tt> class</a> | |
| </ul> | |
| <li><a href="#builtinparsers">Builtin parsers</a> | |
| <ul> | |
| <li><a href="#genericparser">The Generic <tt>parser<t></tt> | |
| parser</a> | |
| <li><a href="#boolparser">The <tt>parser<bool></tt> | |
| specialization</a> | |
| <li><a href="#stringparser">The <tt>parser<string></tt> | |
| specialization</a> | |
| <li><a href="#intparser">The <tt>parser<int></tt> | |
| specialization</a> | |
| <li><a href="#doubleparser">The <tt>parser<double></tt> and | |
| <tt>parser<float></tt> specializations</a> | |
| </ul> | |
| </ol> | |
| <li><a href="#extensionguide">Extension Guide</a> | |
| <ol> | |
| <li><a href="#customparser">Writing a custom parser</a> | |
| <li><a href="#explotingexternal">Exploiting external storage</a> | |
| <li><a href="#dynamicopts">Dynamically adding command line options</a> | |
| </ol> | |
| <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b><p> | |
| </ol><p> | |
| <!-- *********************************************************************** --> | |
| <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0> | |
| <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b> | |
| <a name="introduction">Introduction | |
| </b></font></td></tr></table><ul> | |
| <!-- *********************************************************************** --> | |
| This document describes the CommandLine argument processing library. It will | |
| show you how to use it, and what it can do. The CommandLine library uses a | |
| declarative approach to specifying the command line options that your program | |
| takes. By default, these options declarations implicitly hold the value parsed | |
| for the option declared (of course this <a href="#storage">can be | |
| changed</a>).<p> | |
| Although there are a <b>lot</b> of command line argument parsing libraries out | |
| there in many different languages, none of them fit well with what I needed. By | |
| looking at the features and problems of other libraries, I designed the | |
| CommandLine library to have the following features:<p> | |
| <ol> | |
| <li>Speed: The CommandLine library is very quick and uses little resources. The | |
| parsing time of the library is directly proportional to the number of arguments | |
| parsed, not the the number of options recognized. Additionally, command line | |
| argument values are captured transparently into user defined global variables, | |
| which can be accessed like any other variable (and with the same | |
| performance).<p> | |
| <li>Type Safe: As a user of CommandLine, you don't have to worry about | |
| remembering the type of arguments that you want (is it an int? a string? a | |
| bool? an enum?) and keep casting it around. Not only does this help prevent | |
| error prone constructs, it also leads to dramatically cleaner source code.<p> | |
| <li>No subclasses required: To use CommandLine, you instantiate variables that | |
| correspond to the arguments that you would like to capture, you don't subclass a | |
| parser. This means that you don't have to write <b>any</b> boilerplate code.<p> | |
| <li>Globally accessible: Libraries can specify command line arguments that are | |
| automatically enabled in any tool that links to the library. This is possible | |
| because the application doesn't have to keep a "list" of arguments to pass to | |
| the parser. This also makes supporting <a href="#dynamicopts">dynamically | |
| loaded options</a> trivial.<p> | |
| <li>Cleaner: CommandLine supports enum and other types directly, meaning that | |
| there is less error and more security built into the library. You don't have to | |
| worry about whether your integral command line argument accidentally got | |
| assigned a value that is not valid for your enum type.<p> | |
| <li>Powerful: The CommandLine library supports many different types of | |
| arguments, from simple <a href="#boolparser">boolean flags</a> to <a | |
| href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a | |
| href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a | |
| href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of | |
| arguments</a>. This is possible because CommandLine is...<p> | |
| <li>Extensible: It is very simple to add a new argument type to CommandLine. | |
| Simply specify the parser that you want to use with the command line option when | |
| you declare it. <a href="#customparser">Custom parsers</a> are no problem.<p> | |
| <li>Labor Saving: The CommandLine library cuts down on the amount of grunt work | |
| that you, the user, have to do. For example, it automatically provides a | |
| <tt>--help</tt> option that shows the available command line options for your | |
| tool. Additionally, it does most of the basic correctness checking for you.<p> | |
| <li>Capable: The CommandLine library can handle lots of different forms of | |
| options often found in real programs. For example, <a | |
| href="#positional">positional</a> arguments, <tt>ls</tt> style <a | |
| href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls | |
| -lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a> | |
| options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a | |
| href="#cl::ConsumeAfter">interpreter style options</a>.<p> | |
| </ol> | |
| This document will hopefully let you jump in and start using CommandLine in your | |
| utility quickly and painlessly. Additionally it should be a simple reference | |
| manual to figure out how stuff works. If it is failing in some area (or you | |
| want an extension to the library), nag the author, <a | |
| href="mailto:sabre@nondot.org">Chris Lattner</a>.<p> | |
| <!-- *********************************************************************** --> | |
| </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0><tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b> | |
| <a name="quickstart">Quick Start Guide | |
| </b></font></td></tr></table><ul> | |
| <!-- *********************************************************************** --> | |
| This section of the manual runs through a simple CommandLine'ification of a | |
| basic compiler tool. This is intended to show you how to jump into using the | |
| CommandLine library in your own program, and show you some of the cool things it | |
| can do.<p> | |
| To start out, you need to include the CommandLine header file into your | |
| program:<p> | |
| <pre> | |
| #include "Support/CommandLine.h" | |
| </pre><p> | |
| Additionally, you need to add this as the first line of your main program:<p> | |
| <pre> | |
| int main(int argc, char **argv) { | |
| <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv); | |
| ... | |
| } | |
| </pre><p> | |
| ... which actually parses the arguments and fills in the variable | |
| declarations.<p> | |
| Now that you are ready to support command line arguments, we need to tell the | |
| system which ones we want, and what type of argument they are. The CommandLine | |
| library uses a declarative syntax to model command line arguments with the | |
| global variable declarations that capture the parsed values. This means that | |
| for every command line option that you would like to support, there should be a | |
| global variable declaration to capture the result. For example, in a compiler, | |
| we would like to support the unix standard '<tt>-o <filename></tt>' option | |
| to specify where to put the output. With the CommandLine library, this is | |
| represented like this:<p> | |
| <pre><a name="value_desc_example"> | |
| <a href="#cl::opt">cl::opt</a><string> OutputFilename("<i>o</i>", <a href="#cl::desc">cl::desc</a>("<i>Specify output filename</i>"), <a href="#cl::value_desc">cl::value_desc</a>("<i>filename</i>")); | |
| </pre><p> | |
| This declares a global variable "<tt>OutputFilename</tt>" that is used to | |
| capture the result of the "<tt>o</tt>" argument (first parameter). We specify | |
| that this is a simple scalar option by using the "<tt><a | |
| href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a | |
| href="#list">"<tt>cl::list</tt> template</a>), and tell the CommandLine library | |
| that the data type that we are parsing is a string.<p> | |
| The second and third parameters (which are optional) are used to specify what to | |
| output for the "<tt>--help</tt>" option. In this case, we get a line that looks | |
| like this:<p> | |
| <pre> | |
| USAGE: compiler [options] | |
| OPTIONS: | |
| -help - display available options (--help-hidden for more) | |
| <b>-o <filename> - Specify output filename</b> | |
| </pre> | |
| Because we specified that the command line option should parse using the | |
| <tt>string</tt> data type, the variable declared is automatically usable as a | |
| real string in all contexts that a normal C++ string object may be used. For | |
| example:<p> | |
| <pre> | |
| ... | |
| ofstream Output(OutputFilename.c_str()); | |
| if (Out.good()) ... | |
| ... | |
| </pre><p> | |
| There are many different options that you can use to customize the command line | |
| option handling library, but the above example shows the general interface to | |
| these options. The options can be specified in any order, and are specified | |
| with helper functions like <a href="#cl::desc"><tt>cl::desc(...)</tt></a>, so | |
| there are no positional dependencies to remember. The available options are | |
| discussed in detail in the <a href="#referenceguide">Reference Guide</a>.<p> | |
| Continuing the example, we would like to have our compiler take an input | |
| filename as well as an output filename, but we do not want the input filename to | |
| be specified with a hyphen (ie, not <tt>-filename.c</tt>). To support this | |
| style of argument, the CommandLine library allows for <a | |
| href="#positional">positional</a> arguments to be specified for the program. | |
| These positional arguments are filled with command line parameters that are not | |
| in option form. We use this feature like this:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><string> InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>"), <a href="#cl::init">cl::init</a>("<i>-</i>")); | |
| </pre> | |
| This declaration indicates that the first positional argument should be treated | |
| as the input filename. Here we use the <tt><a | |
| href="#cl::init">cl::init</a></tt> option to specify an initial value for the | |
| command line option, which is used if the option is not specified (if you do not | |
| specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then | |
| the default constructor for the data type is used to initialize the value). | |
| Command line options default to being optional, so if we would like to require | |
| that the user always specify an input filename, we would add the <tt><a | |
| href="#cl::Required">cl::Required</a></tt> flag, and we could eliminate the | |
| <tt><a href="#cl::init">cl::init</a></tt> modifier, like this:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><string> InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>"), <b><a href="#cl::Required">cl::Required</a></b>); | |
| </pre> | |
| Again, the CommandLine library does not require the options to be specified in | |
| any particular order, so the above declaration is equivalent to:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><string> InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::Required">cl::Required</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>")); | |
| </pre> | |
| By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag, the | |
| CommandLine library will automatically issue an error if the argument is not | |
| specified, which shifts all of the command line option verification code out of | |
| your application into the library. This is just one example of how using flags | |
| can alter the default behaviour of the library, on a per-option basis. By | |
| adding one of the declarations above, the <tt>--help</tt> option synopsis is now | |
| extended to:<p> | |
| <pre> | |
| USAGE: compiler [options] <b><input file></b> | |
| OPTIONS: | |
| -help - display available options (--help-hidden for more) | |
| -o <filename> - Specify output filename | |
| </pre> | |
| ... indicating that an input filename is expected.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="bool">Boolean Arguments | |
| </b></font></td></tr></table><ul> | |
| In addition to input and output filenames, we would like the compiler example to | |
| support three boolean flags: "<tt>-f</tt>" to force overwriting of the output | |
| file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards | |
| compatibility with some of our users. We can support these by declaring options | |
| of boolean type like this:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>")); | |
| <a href="#cl::opt">cl::opt</a><bool> Quiet ("<i>quiet</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>")); | |
| <a href="#cl::opt">cl::opt</a><bool> Quiet2("<i>q</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>"), <a href="#cl::Hidden">cl::Hidden</a>); | |
| </pre><p> | |
| This does what you would expect: it declares three boolean variables | |
| ("<tt>Force</tt>", "<tt>Quiet</tt>", and "<tt>Quiet2</tt>") to recognize these | |
| options. Note that the "<tt>-q</tt>" option is specified with the "<a | |
| href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it | |
| from being shown by the standard "<tt>--help</tt>" output (note that it is still | |
| shown in the "<tt>--help-hidden</tt>" output).<p> | |
| The CommandLine library uses a <a href="#builtinparsers">different parser</a> | |
| for different data types. For example, in the string case, the argument passed | |
| to the option is copied literally into the content of the string variable... we | |
| obviously cannot do that in the boolean case, however, so we must use a smarter | |
| parser. In the case of the boolean parser, it allows no options (in which case | |
| it assigns the value of true to the variable), or it allows the values | |
| "<tt>true</tt>" or "<tt>false</tt>" to be specified, allowing any of the | |
| following inputs:<p> | |
| <pre> | |
| compiler -f # No value, 'Force' == true | |
| compiler -f=true # Value specified, 'Force' == true | |
| compiler -f=TRUE # Value specified, 'Force' == true | |
| compiler -f=FALSE # Value specified, 'Force' == false | |
| </pre> | |
| ... you get the idea. The <a href="#boolparser">bool parser</a> just turns the | |
| string values into boolean values, and rejects things like '<tt>compiler | |
| -f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a | |
| href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work | |
| like you would expect, using the '<tt>strtol</tt>' and '<tt>strtod</tt>' C | |
| library calls to parse the string value into the specified data type.<p> | |
| With the declarations above, "<tt>compiler --help</tt>" emits this:<p> | |
| <pre> | |
| USAGE: compiler [options] <input file> | |
| OPTIONS: | |
| <b>-f - Overwrite output files</b> | |
| -o - Override output filename | |
| <b>-quiet - Don't print informational messages</b> | |
| -help - display available options (--help-hidden for more) | |
| </pre><p> | |
| and "<tt>opt --help-hidden</tt>" prints this:<p> | |
| <pre> | |
| USAGE: compiler [options] <input file> | |
| OPTIONS: | |
| -f - Overwrite output files | |
| -o - Override output filename | |
| <b>-q - Don't print informational messages</b> | |
| -quiet - Don't print informational messages | |
| -help - display available options (--help-hidden for more) | |
| </pre><p> | |
| This brief example has shown you how to use the '<tt><a | |
| href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line | |
| arguments. In addition to simple scalar arguments, the CommandLine library also | |
| provides primitives to support CommandLine option <a href="#alias">aliases</a>, | |
| and <a href="#list">lists</a> of options.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="alias">Argument Aliases | |
| </b></font></td></tr></table><ul> | |
| So far, the example works well, except for the fact that we need to check the | |
| quiet condition like this now:<p> | |
| <pre> | |
| ... | |
| if (!Quiet && !Quiet2) printInformationalMessage(...); | |
| ... | |
| </pre><p> | |
| ... which is a real pain! Instead of defining two values for the same | |
| condition, we can use the "<tt><a href="#cl::alias">cl::alias</a></tt>" class to make the "<tt>-q</tt>" | |
| option an <b>alias</b> for the "<tt>-quiet</tt>" option, instead of providing | |
| a value itself:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>")); | |
| <a href="#cl::opt">cl::opt</a><bool> Quiet ("<i>quiet</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>")); | |
| <a href="#cl::alias">cl::alias</a> QuietA("<i>q</i>", <a href="#cl::desc">cl::desc</a>("<i>Alias for -quiet</i>"), <a href="#cl::aliasopt">cl::aliasopt</a>(Quiet)); | |
| </pre><p> | |
| The third line (which is the only one we modified from above) defines a | |
| "<tt>-q</tt> alias that updates the "<tt>Quiet</tt>" variable (as specified by | |
| the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is | |
| specified. Because aliases do not hold state, the only thing the program has to | |
| query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is | |
| that they automatically hide themselves from the <tt>-help</tt> output | |
| (although, again, they are still visible in the <tt>--help-hidden | |
| output</tt>).<p> | |
| Now the application code can simply use:<p> | |
| <pre> | |
| ... | |
| if (!Quiet) printInformationalMessage(...); | |
| ... | |
| </pre><p> | |
| ... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>" can be used to specify an | |
| alternative name for any variable type, and has many uses.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="onealternative">Selecting an alternative from a set of possibilities | |
| </b></font></td></tr></table><ul> | |
| So far, we have seen how the CommandLine library handles builtin types like | |
| <tt>std::string</tt>, <tt>bool</tt> and <tt>int</tt>, but how does it handle | |
| things it doesn't know about, like enums or '<tt>int*</tt>'s?<p> | |
| The answer is that it uses a table driven generic parser (unless you specify | |
| your own parser, as described in the <a href="#extensionguide">Extension | |
| Guide</a>). This parser maps literal strings to whatever type is required, are | |
| requires you to tell it what this mapping should be.<p> | |
| Lets say that we would like to add four optimizations levels to our optimizer, | |
| using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>", "<tt>-O1</tt>", and | |
| "<tt>-O2</tt>". We could easily implement this with boolean options like above, | |
| but there are several problems with this strategy:<p> | |
| <ol> | |
| <li>A user could specify more than one of the options at a time, for example, | |
| "<tt>opt -O3 -O2</tt>". The CommandLine library would not be able to catch this | |
| erroneous input for us. | |
| <li>We would have to test 4 different variables to see which ones are set. | |
| <li>This doesn't map to the numeric levels that we want... so we cannot easily | |
| see if some level >= "<tt>-O1</tt>" is enabled. | |
| </ol><p> | |
| To cope with these problems, we can use an enum value, and have the CommandLine | |
| library fill it in with the appropriate level directly, which is used like | |
| this:<p> | |
| <pre> | |
| enum OptLevel { | |
| g, O1, O2, O3 | |
| }; | |
| <a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"), | |
| <a href="#cl::values">cl::values</a>( | |
| clEnumVal(g , "<i>No optimizations, enable debugging</i>"), | |
| clEnumVal(O1, "<i>Enable trivial optimizations</i>"), | |
| clEnumVal(O2, "<i>Enable default optimizations</i>"), | |
| clEnumVal(O3, "<i>Enable expensive optimizations</i>"), | |
| 0)); | |
| ... | |
| if (OptimizationLevel >= O2) doPartialRedundancyElimination(...); | |
| ... | |
| </pre><p> | |
| This declaration defines a variable "<tt>OptimizationLevel</tt>" of the | |
| "<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values | |
| that are listed in the declaration (Note that the declaration list must be | |
| terminated with the "<tt>0</tt>" argument!). The CommandLine library enforces | |
| that the user can only specify one of the options, and it ensure that only valid | |
| enum values can be specified. The "<tt>clEnumVal</tt>" macros ensure that the | |
| command line arguments matched the enum values. With this option added, our | |
| help output now is:<p> | |
| <pre> | |
| USAGE: compiler [options] <input file> | |
| OPTIONS: | |
| <b>Choose optimization level: | |
| -g - No optimizations, enable debugging | |
| -O1 - Enable trivial optimizations | |
| -O2 - Enable default optimizations | |
| -O3 - Enable expensive optimizations</b> | |
| -f - Overwrite output files | |
| -help - display available options (--help-hidden for more) | |
| -o <filename> - Specify output filename | |
| -quiet - Don't print informational messages | |
| </pre> | |
| In this case, it is sort of awkward that flag names correspond directly to enum | |
| names, because we probably don't want a enum definition named "<tt>g</tt>" in | |
| our program. Because of this, we can alternatively write this example like | |
| this:<p> | |
| <pre> | |
| enum OptLevel { | |
| Debug, O1, O2, O3 | |
| }; | |
| <a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"), | |
| <a href="#cl::values">cl::values</a>( | |
| clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"), | |
| clEnumVal(O1 , "<i>Enable trivial optimizations</i>"), | |
| clEnumVal(O2 , "<i>Enable default optimizations</i>"), | |
| clEnumVal(O3 , "<i>Enable expensive optimizations</i>"), | |
| 0)); | |
| ... | |
| if (OptimizationLevel == Debug) outputDebugInfo(...); | |
| ... | |
| </pre><p> | |
| By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we can | |
| directly specify the name that the flag should get. In general a direct mapping | |
| is nice, but sometimes you can't or don't want to preserve the mapping, which is | |
| when you would use it.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="namedalternatives">Named Alternatives | |
| </b></font></td></tr></table><ul> | |
| Another useful argument form is a named alternative style. We shall use this | |
| style in our compiler to specify different debug levels that can be used. | |
| Instead of each debug level being its own switch, we want to support the | |
| following options, of which only one can be specified at a time: | |
| "<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>", | |
| "<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as | |
| our optimization level flags, but we also specify an option name. For this | |
| case, the code looks like this:<p> | |
| <pre> | |
| enum DebugLev { | |
| nodebuginfo, quick, detailed | |
| }; | |
| // Enable Debug Options to be specified on the command line | |
| <a href="#cl::opt">cl::opt</a><DebugLev> DebugLevel("<i>debug_level</i>", <a href="#cl::desc">cl::desc</a>("<i>Set the debugging level:</i>"), | |
| <a href="#cl::values">cl::values</a>( | |
| clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"), | |
| clEnumVal(quick, "<i>enable quick debug information</i>"), | |
| clEnumVal(detailed, "<i>enable detailed debug information</i>"), | |
| 0)); | |
| </pre> | |
| This definition defines an enumerated command line variable of type "<tt>enum | |
| DebugLev</tt>", which works exactly the same way as before. The difference here | |
| is just the interface exposed to the user of your program and the help output by | |
| the "<tt>--help</tt>" option:<p> | |
| <pre> | |
| USAGE: compiler [options] <input file> | |
| OPTIONS: | |
| Choose optimization level: | |
| -g - No optimizations, enable debugging | |
| -O1 - Enable trivial optimizations | |
| -O2 - Enable default optimizations | |
| -O3 - Enable expensive optimizations | |
| <b>-debug_level - Set the debugging level: | |
| =none - disable debug information | |
| =quick - enable quick debug information | |
| =detailed - enable detailed debug information</b> | |
| -f - Overwrite output files | |
| -help - display available options (--help-hidden for more) | |
| -o <filename> - Specify output filename | |
| -quiet - Don't print informational messages | |
| </pre><p> | |
| Again, the only structural difference between the debug level declaration and | |
| the optimiation level declaration is that the debug level declaration includes | |
| an option name (<tt>"debug_level"</tt>), which automatically changes how the | |
| library processes the argument. The CommandLine library supports both forms so | |
| that you can choose the form most appropriate for your application.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="list">Parsing a list of options | |
| </b></font></td></tr></table><ul> | |
| Now that we have the standard run of the mill argument types out of the way, | |
| lets get a little wild and crazy. Lets say that we want our optimizer to accept | |
| a <b>list</b> of optimizations to perform, allowing duplicates. For example, we | |
| might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In | |
| this case, the order of the arguments and the number of appearances is very | |
| important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>" | |
| template is for. First, start by defining an enum of the optimizations that you | |
| would like to perform:<p> | |
| <pre> | |
| enum Opts { | |
| // 'inline' is a C++ keyword, so name it 'inlining' | |
| dce, constprop, inlining, strip | |
| }; | |
| </pre><p> | |
| Then define your "<tt><a href="#cl::list">cl::list</a></tt>" variable:<p> | |
| <pre> | |
| <a href="#cl::list">cl::list</a><Opts> OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"), | |
| <a href="#cl::values">cl::values</a>( | |
| clEnumVal(dce , "<i>Dead Code Elimination</i>"), | |
| clEnumVal(constprop , "<i>Constant Propagation</i>"), | |
| clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"), | |
| clEnumVal(strip , "<i>Strip Symbols</i>"), | |
| 0)); | |
| </pre><p> | |
| This defines a variable that is conceptually of the type | |
| "<tt>std::vector<enum Opts></tt>". Thus, you can access it with standard | |
| vector methods:<p> | |
| <pre> | |
| for (unsigned i = 0; i != OptimizationList.size(); ++i) | |
| switch (OptimizationList[i]) | |
| ... | |
| </pre> | |
| ... to iterate through the list of options specified.<p> | |
| Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is completely general and may be used | |
| with any data types or other arguments that you can use with the | |
| "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One especially useful way to use a list is to | |
| capture all of the positional arguments together if there may be more than one | |
| specified. In the case of a linker, for example, the linker takes several | |
| '<tt>.o</tt>' files, and needs to capture them into a list. This is naturally | |
| specified as:<p> | |
| <pre> | |
| ... | |
| <a href="#cl::list">cl::list</a><std::string> InputFilenames(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<Input files>"), <a href="#cl::OneOrMore">cl::OneOrMore</a>); | |
| ... | |
| </pre><p> | |
| This variable works just like a "<tt>vector<string></tt>" object. As | |
| such, accessing the list is simple, just like above. In this example, we used | |
| the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the | |
| CommandLine library that it is an error if the user does not specify any | |
| <tt>.o</tt> files on our command line. Again, this just reduces the amount of | |
| checking we have to do.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="description">Adding freeform text to help output | |
| </b></font></td></tr></table><ul> | |
| As our program grows and becomes more mature, we may decide to put summary | |
| information about what it does into the help output. The help output is styled | |
| to look similar to a Unix <tt>man</tt> page, providing concise information about | |
| a program. Unix <tt>man</tt> pages, however often have a description about what | |
| the program does. To add this to your CommandLine program, simply pass a third | |
| argument to the <a | |
| href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a> | |
| call in main. This additional argument is then printed as the overview | |
| information for your program, allowing you to include any additional information | |
| that you want. For example:<p> | |
| <pre> | |
| int main(int argc, char **argv) { | |
| <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n" | |
| " This program blah blah blah...\n"); | |
| ... | |
| } | |
| </pre><p> | |
| Would yield the help output: | |
| <pre> | |
| <b>OVERVIEW: CommandLine compiler example | |
| This program blah blah blah...</b> | |
| USAGE: compiler [options] <input file> | |
| OPTIONS: | |
| ... | |
| -help - display available options (--help-hidden for more) | |
| -o <filename> - Specify output filename | |
| </pre><p> | |
| <!-- *********************************************************************** --> | |
| </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0><tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b> | |
| <a name="referenceguide">Reference Guide | |
| </b></font></td></tr></table><ul> | |
| <!-- *********************************************************************** --> | |
| Now that you know the basics of how to use the CommandLine library, this section | |
| will give you the detailed information you need to tune how command line options | |
| work, as well as information on more "advanced" command line option processing | |
| capabilities.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="positional">Positional Arguments | |
| </b></font></td></tr></table><ul> | |
| Positional arguments are those arguments that are not named, and are not | |
| specified with a hyphen. Positional arguments should be used when an option is | |
| specified by its position alone. For example, the standard Unix <tt>grep</tt> | |
| tool takes a regular expression argument, and an optional filename to search | |
| through (which defaults to standard input if a filename is not specified). | |
| Using the CommandLine library, this would be specified as:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><string> Regex (<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><regular expression></i>"), <a href="#cl::Required">cl::Required</a>); | |
| <a href="#cl::opt">cl::opt</a><string> Filename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>"), <a href="#cl::init">cl::init</a>("<i>-</i>")); | |
| </pre> | |
| Given these two option declarations, the <tt>--help</tt> output for our grep | |
| replacement would look like this:<p> | |
| <pre> | |
| USAGE: spiffygrep [options] <b><regular expression> <input file></b> | |
| OPTIONS: | |
| -help - display available options (--help-hidden for more) | |
| </pre> | |
| ... and the resultant program could be used just like the standard <tt>grep</tt> | |
| tool.<p> | |
| Positional arguments are sorted by their order of construction. This means that | |
| command line options will be ordered according to how they are listed in a .cpp | |
| file, but will not have an ordering defined if they positional arguments are | |
| defined in multiple .cpp files. The fix for this problem is simply to define | |
| all of your positional arguments in one .cpp file.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="--"><h4><hr size=0>Specifying positional options with hyphens</h4><ul> | |
| Sometimes you may want to specify a value to your positional argument that | |
| starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At | |
| first, you will have trouble doing this, because it will try to find an argument | |
| named '<tt>-foo</tt>', and will fail (and single quotes will not save you). | |
| Note that the system <tt>grep</tt> has the same problem:<p> | |
| <pre> | |
| $ spiffygrep '-foo' test.txt | |
| Unknown command line argument '-foo'. Try: spiffygrep --help' | |
| $ grep '-foo' test.txt | |
| grep: illegal option -- f | |
| grep: illegal option -- o | |
| grep: illegal option -- o | |
| Usage: grep -hblcnsviw pattern file . . . | |
| </pre><p> | |
| The solution for this problem is the same for both your tool and the system | |
| version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on | |
| the command line, it is telling the program that all options after the | |
| '<tt>--</tt>' should be treated as positional arguments, not options. Thus, we | |
| can use it like this:<p> | |
| <pre> | |
| $ spiffygrep -- -foo test.txt | |
| ...output... | |
| </pre><p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="cl::ConsumeAfter"><h4><hr size=0>The <tt>cl::ConsumeAfter</tt> modifier</h4><ul> | |
| The <tt>cl::ConsumeAfter</tt> <a href="#formatting">formatting option</a> is | |
| used to construct programs that use "interpreter style" option processing. With | |
| this style of option processing, all arguments specified after the last | |
| positional argument are treated as special interpreter arguments that are not | |
| interpreted by the command line argument.<p> | |
| As a concrete example, lets say we are developing a replacement for the standard | |
| Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first you | |
| specify options to the shell itself (like <tt>-x</tt> which turns on trace | |
| output), then you specify the name of the script to run, then you specify | |
| arguments to the script. These arguments to the script are parsed by the bourne | |
| shell command line option processor, but are not interpreted as options to the | |
| shell itself. Using the CommandLine library, we would specify this as:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><string> Script(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input script></i>"), <a href="#cl::init">cl::init</a>("-")); | |
| <a href="#cl::list">cl::list</a><string> Argv(<a href="#cl::ConsumeAfter">cl::ConsumeAfter</a>, <a href="#cl::desc">cl::desc</a>("<i><program arguments>...</i>")); | |
| <a href="#cl::opt">cl::opt</a><bool> Trace("<i>x</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable trace output</i>")); | |
| </pre><p> | |
| which automatically provides the help output:<p> | |
| <pre> | |
| USAGE: spiffysh [options] <b><input script> <program arguments>...</b> | |
| OPTIONS: | |
| -help - display available options (--help-hidden for more) | |
| <b>-x - Enable trace output</b> | |
| </pre><p> | |
| At runtime, if we run our new shell replacement as '<tt>spiffysh -x test.sh -a | |
| -x -y bar</tt>', the <tt>Trace</tt> variable will be set to true, the | |
| <tt>Script</tt> variable will be set to "<tt>test.sh</tt>", and the | |
| <tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because | |
| they were specified after the last positional argument (which is the script | |
| name).<p> | |
| There are several limitations to when <tt>cl::ConsumeAfter</tt> options can be | |
| specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified per | |
| program, there must be at least one <a href="#positional">positional | |
| argument</a> specified, and the <tt>cl::ConsumeAfter</tt> option should be a <a | |
| href="#cl::list">cl::list</a> option.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="storage">Internal vs External Storage | |
| </b></font></td></tr></table><ul> | |
| By default, all command line options automatically hold the value that they | |
| parse from the command line. This is very convenient in the common case, | |
| especially when combined with the ability to define command line options in the | |
| files that use them. This is called the internal storage model.<p> | |
| Sometimes, however, it is nice to separate the command line option processing | |
| code from the storage of the value parsed. For example, lets say that we have a | |
| '<tt>-debug</tt>' option that we would like to use to enable debug information | |
| across the entire body of our program. In this case, the boolean value | |
| controlling the debug code should be globally accessable (in a header file, for | |
| example) yet the command line option processing code should not be exposed to | |
| all of these clients (requiring lots of .cpp files to #include | |
| <tt>CommandLine.h</tt>).<p> | |
| To do this, set up your .h file with your option, like this for example:<p> | |
| <pre> | |
| <i>// DebugFlag.h - Get access to the '-debug' command line option | |
| // | |
| // DebugFlag - This boolean is set to true if the '-debug' command line option | |
| // is specified. This should probably not be referenced directly, instead, use | |
| // the DEBUG macro below. | |
| //</i> | |
| extern bool DebugFlag; | |
| <i>// DEBUG macro - This macro should be used by code to emit debug information. | |
| // In the '-debug' option is specified on the command line, and if this is a | |
| // debug build, then the code specified as the option to the macro will be | |
| // executed. Otherwise it will not be. Example: | |
| // | |
| // DEBUG(cerr << "Bitset contains: " << Bitset << "\n"); | |
| //</i> | |
| <font color=red>#ifdef NDEBUG | |
| #define DEBUG(X) | |
| #else | |
| #define DEBUG(X)</font> \ | |
| do { if (DebugFlag) { X; } } while (0) | |
| <font color=red>#endif</font> | |
| </pre> | |
| This allows clients to blissfully use the <tt>DEBUG()</tt> macro, or the | |
| <tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to | |
| set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass | |
| an additial argument to our command line argument processor, and we specify | |
| where to fill in with the <a href="#cl::location">cl::location</a> attribute:<p> | |
| <pre> | |
| bool DebugFlag; <i>// the actual value</i> | |
| static <a href="#cl::opt">cl::opt</a><bool, true> <i>// The parser</i> | |
| Debug("<i>debug</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable debug output</i>")</a>, <a href="#cl::Hidden">cl::Hidden</a>, | |
| <a href="#cl::location">cl::location</a>(DebugFlag)); | |
| </pre> | |
| In the above example, we specify "<tt>true</tt>" as the second argument to the | |
| <a href="#cl::opt">cl::opt</a> template, indicating that the template should not | |
| maintain a copy of the value itself. In addition to this, we specify the <a | |
| href="#cl::location">cl::location</a> attribute, so that <tt>DebugFlag</tt> is | |
| automatically set.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="attributes">Option Attributes | |
| </b></font></td></tr></table><ul> | |
| This section describes the basic attributes that you can specify on options.<p> | |
| <ul> | |
| <li>The option name attribute (which is required for all options, except <a | |
| href="#positional">positional options</a>) specifies what the option name is. | |
| This option is specified in simple double quotes:<p> | |
| <pre> | |
| <a href="#cl::opt">cl::opt</a><<b>bool</b>> Quiet("<i>quiet</i>"); | |
| </pre><p> | |
| <li><a name="cl::desc">The <b><tt>cl::desc</tt></b> attribute specifies a | |
| description for the option to be shown in the <tt>--help</tt> output for the | |
| program.<p> | |
| <li><a name="cl::value_desc">The <b><tt>cl::value_desc</tt></b> attribute | |
| specifies a string that can be used to fine tune the <tt>--help</tt> output for | |
| a command line option. Look <a href="#value_desc_example">here</a> for an | |
| example.<p> | |
| <li><a name="cl::init">The <b><tt>cl::init</tt></b> attribute specifies an | |
| inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is | |
| not specified then the command line option value defaults to the value created | |
| by the default constructor for the type. <b>Warning</b>: If you specify both | |
| <b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option, | |
| you must specify <b><tt>cl::location</tt></b> first, so that when the | |
| command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the | |
| initial value. (You will get an error at runtime if you don't put them in | |
| the right order.)<p> | |
| <li><a name="cl::location">The <b><tt>cl::location</tt></b> attribute where to | |
| store the value for a parsed command line option if using external storage. See | |
| the section on <a href="#storage">Internal vs External Storage</a> for more | |
| information.<p> | |
| <li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b> attribute specifies | |
| which option a <a href="#cl::alias">cl::alias</a> option is an alias for.<p> | |
| <li><a name="cl::values">The <b><tt>cl::values</tt></b> attribute specifies the | |
| string-to-value mapping to be used by the generic parser. It takes a <b>null | |
| terminated</b> list of (option, value, description) triplets that specify the | |
| option name, the value mapped to, and the description shown in the | |
| <tt>--help</tt> for the tool. Because the generic parser is used most frequently with enum values, two macros are often useful:<p> | |
| <ol> | |
| <li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b> macro is used as a nice | |
| simple way to specify a triplet for an enum. This macro automatically makes the | |
| option name be the same as the enum name. The first option to the macro is the | |
| enum, the second is the description for the command line option.<p> <li><a | |
| name="clEnumValN">The <b><tt>clEnumValN</tt></b> macro is used to specify macro | |
| options where the option name doesn't equal the enum name. For this macro, the | |
| first argument is the enum value, the second is the flag name, and the second is | |
| the description.<p> | |
| </ol> | |
| You will get a compile time error if you try to use cl::values with a parser | |
| that does not support it.<p> | |
| </ul> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="modifiers">Option Modifiers | |
| </b></font></td></tr></table><ul> | |
| Option modifiers are the flags and expressions that you pass into the | |
| constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a | |
| href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to | |
| tweak how options are parsed and how <tt>--help</tt> output is generated to fit | |
| your application well.<p> | |
| These options fall into five main catagories:<p> | |
| <ol> | |
| <li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a> | |
| <li><a href="#numoccurances">Controlling the number of occurances | |
| required and allowed</a> | |
| <li><a href="#valrequired">Controlling whether or not a value must be | |
| specified</a> | |
| <li><a href="#formatting">Controlling other formatting options</a> | |
| <li><a href="#misc">Miscellaneous option modifiers</a> | |
| </ol><p> | |
| It is not possible to specify two options from the same catagory (you'll get a | |
| runtime error) to a single option, except for options in the miscellaneous | |
| catagory. The CommandLine library specifies defaults for all of these settings | |
| that are the most useful in practice and the most common, which mean that you | |
| usually shouldn't have to worry about these.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="hiding"><h4><hr size=0>Hiding an option from <tt>--help</tt> output</h4><ul> | |
| The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and <tt>cl::ReallyHidden</tt> | |
| modifiers are used to control whether or not an option appears in the | |
| <tt>--help</tt> and <tt>--help-hidden</tt> output for the compiled program:<p> | |
| <ul> | |
| <a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b> modifier (which is the | |
| default for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a | |
| href="#cl::list">cl::list</a></tt> options), indicates the option is to appear | |
| in both help listings.<p> | |
| <a name="cl::Hidden">The <b><tt>cl::Hidden</tt></b> modifier (which is the | |
| default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that | |
| the option should not appear in the <tt>--help</tt> output, but should appear in | |
| the <tt>--help-hidden</tt> output.<p> | |
| <a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b> modifier, | |
| indicates that the option should not appear in any help output.<p> | |
| </ul> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="numoccurances"><h4><hr size=0>Controlling the number of occurances required and allowed</h4><ul> | |
| This group of options is used to control how many time an option is allowed (or | |
| required) to be specified on the command line of your program. Specifying a | |
| value for this setting allows the CommandLine library to do error checking for | |
| you.<p> | |
| The allowed values for this option group are:<p> | |
| <ul> | |
| <a name="cl::Optional">The <b><tt>cl::Optional</tt></b> modifier (which is the | |
| default for the <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a | |
| href="#cl::alias">cl::alias</a></tt> classes) indicates that your program will | |
| allow either zero or one occurance of the option to be specified.<p> | |
| <a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b> modifier (which is | |
| the default for the <tt><a href="#cl::list">cl::list</a></tt> class) indicates | |
| that your program will allow the option to be specified zero or more times.<p> | |
| <a name="cl::Required">The <b><tt>cl::Required</tt></b> modifier indicates that | |
| the specified option must be specified exactly one time.<p> | |
| <a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b> modifier indicates | |
| that the option must be specified at least one time.<p> | |
| The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a | |
| href="#positional">Positional arguments section</a><p> | |
| </ul> | |
| If an option is not specified, then the value of the option is equal to the | |
| value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If | |
| the <tt><a href="#cl::init">cl::init</a></tt> attribute is not specified, the | |
| option value is initialized with the default constructor for the data type.<p> | |
| If an option is specified multiple times for an option of the <tt><a | |
| href="#cl::opt">cl::opt</a></tt> class, only the last value will be retained.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="valrequired"><h4><hr size=0>Controlling whether or not a value must be specified</h4><ul> | |
| This group of options is used to control whether or not the option allows a | |
| value to be present. In the case of the CommandLine library, a value is either | |
| specified with an equal sign (e.g. '<tt>-index-depth=17</tt>') or as a trailing | |
| string (e.g. '<tt>-o a.out</tt>').<p> | |
| The allowed values for this option group are:<p> | |
| <ul> | |
| <a name="cl::ValueOptional">The <b><tt>cl::ValueOptional</tt></b> modifier | |
| (which is the default for <tt>bool</tt> typed options) specifies that it is | |
| acceptable to have a value, or not. A boolean argument can be enabled just by | |
| appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'. | |
| If an option is specified with this mode, it is illegal for the value to be | |
| provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To | |
| get this behavior, you must use the <a | |
| href="#cl::ValueRequired">cl::ValueRequired</a> modifier.<p> | |
| <a name="cl::ValueRequired">The <b><tt>cl::ValueRequired</tt></b> modifier | |
| (which is the default for all other types except for <a | |
| href="#onealternative">unnamed alternatives using the generic parser</a>) | |
| specifies that a value must be provided. This mode informs the command line | |
| library that if an option is not provides with an equal sign, that the next | |
| argument provided must be the value. This allows things like '<tt>-o | |
| a.out</tt>' to work.<p> | |
| <a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b> modifier | |
| (which is the default for <a href="#onealternative">unnamed alternatives using | |
| the generic parser</a>) indicates that it is a runtime error for the user to specify a value. This can be provided to disallow users from providing options to boolean options (like '<tt>-foo=true</tt>').<p> | |
| </ul> | |
| In general, the default values for this option group work just like you would | |
| want them to. As mentioned above, you can specify the <a | |
| href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean | |
| argument to restrict your command line parser. These options are mostly useful | |
| when <a href="#extensionguide">extending the library</a>.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="formatting"><h4><hr size=0>Controlling other formatting options</h4><ul> | |
| The formatting option group is used to specify that the command line option has | |
| special abilities and is otherwise different from other command line arguments. | |
| As usual, you can only specify at most one of these arguments.<p> | |
| <ul> | |
| <a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b> modifier | |
| (which is the default all options) specifies that this option is "normal".<p> | |
| <a name="cl::Positional">The <b><tt>cl::Positional</tt></b> modifier specifies | |
| that this is a positional argument, that does not have a command line option | |
| associated with it. See the <a href="#positional">Positional Arguments</a> | |
| section for more information.<p> | |
| The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier | |
| specifies that this option is used to capture "interpreter style" arguments. See <a href="#cl::ConsumeAfter">this section for more information</a>.<p> | |
| <a name="cl::Prefix">The <b><tt>cl::Prefix</tt></b> modifier specifies that this | |
| option prefixes its value. With 'Prefix' options, there is no equal sign that | |
| separates the value from the option name specified. This is useful for | |
| processing odd arguments like '<tt>-lmalloc -L/usr/lib'</tt> in a linker tool. | |
| Here, the '<tt>l</tt>' and '<tt>L</tt>' options are normal string (list) | |
| options, that have the <a href="#cl::Prefix">cl::Prefix</a> modifier added to | |
| allow the CommandLine library to recognize them. Note that <a | |
| href="#cl::Prefix">cl::Prefix</a> options must not have the <a | |
| href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier specified.<p> | |
| <a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b> modifier is used to | |
| implement unix style tools (like <tt>ls</tt>) that have lots of single letter | |
| arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>' | |
| command actually enables four different options, all of which are single | |
| letters. Note that <a href="#cl::Grouping">cl::Grouping</a> options cannot have | |
| values.<p> | |
| </ul> | |
| The CommandLine library does not restrict how you use the <a | |
| href="#cl::Prefix">cl::Prefix</a> or <a href="#cl::Grouping">cl::Grouping</a> | |
| modifiers, but it is possible to specify ambiguous argument settings. Thus, it | |
| is possible to have multiple letter options that are prefix or grouping options, | |
| and they will still work as designed.<p> | |
| To do this, the CommandLine library uses a greedy algorithm to parse the input | |
| option into (potentially multiple) prefix and grouping options. The strategy | |
| basically looks like this:<p> | |
| <tt>parse(string OrigInput) {</tt> | |
| <ol> | |
| <li><tt>string input = OrigInput;</tt> | |
| <li><tt>if (isOption(input)) return getOption(input).parse();</tt> <i>// Normal option</i> | |
| <li><tt>while (!isOption(input) && !input.empty()) input.pop_back();</tt> <i>// Remove the last letter</i> | |
| <li><tt>if (input.empty()) return error();</tt> <i>// No matching option</i> | |
| <li><tt>if (getOption(input).isPrefix())<br> | |
| return getOption(input).parse(input);</tt> | |
| <li><tt>while (!input.empty()) { <i>// Must be grouping options</i><br> | |
| getOption(input).parse();<br> | |
| OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br> | |
| input = OrigInput;<br> | |
| while (!isOption(input) && !input.empty()) input.pop_back();<br> | |
| }</tt> | |
| <li><tt>if (!OrigInput.empty()) error();</tt> | |
| </tt> | |
| </ol> | |
| <tt>}</tt><p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="misc"><h4><hr size=0>Miscellaneous option modifiers</h4><ul> | |
| The miscellaneous option modifiers are the only flags where you can specify more | |
| than one flag from the set: they are not mutually exclusive. These flags | |
| specify boolean properties that modify the option.<p> | |
| <ul> | |
| <a name="cl::CommaSeparated">The <b><tt>cl::CommaSeparated</tt></b> modifier | |
| indicates that any commas specified for an option's value should be used to | |
| split the value up into multiple values for the option. For example, these two | |
| options are equivalent when <tt>cl::CommaSeparated</tt> is specified: | |
| "<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only | |
| makes sense to be used in a case where the option is allowed to accept one or | |
| more values (i.e. it is a <a href="#cl::list">cl::list</a> option).<p> | |
| </ul> | |
| So far, the only miscellaneous option modifier is the | |
| <tt>cl::CommaSeparated</tt> modifier.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="toplevel">Top-Level Classes and Functions | |
| </b></font></td></tr></table><ul> | |
| Despite all of the builtin flexibility, the CommandLine option library really | |
| only consists of one function (<a | |
| href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>) | |
| and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a | |
| href="#cl::list"><tt>cl::list</tt></a>, and <a | |
| href="#cl::alias"><tt>cl::alias</tt></a>. This section describes these three | |
| classes in detail.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="cl::ParseCommandLineOptions"><h4><hr size=0>The | |
| <tt>cl::ParseCommandLineOptions</tt> function</h4><ul> | |
| The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called | |
| directly from <tt>main</tt>, and is used to fill in the values of all of the | |
| command line option variables once <tt>argc</tt> and <tt>argv</tt> are | |
| available.<p> | |
| The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters | |
| (<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter | |
| which holds <a href="#description">additional extra text</a> to emit when the | |
| <tt>--help</tt> option is invoked.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="cl::ParseEnvironmentOptions"><h4><hr size=0>The | |
| <tt>cl::ParseEnvironmentOptions</tt> function</h4><ul> | |
| The <tt>cl::ParseEnvironmentOptions</tt> | |
| function has mostly the same effects as | |
| <a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>, | |
| except that it is designed to take values for options from an | |
| environment variable, for those cases in which reading the | |
| command line is not convenient or not desired. It fills in | |
| the values of all the command line option variables just like | |
| <a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a> | |
| does.<p> | |
| It takes three parameters: first, the name of the program (since <tt>argv</tt> | |
| may not be available, it can't just look in <tt>argv[0]</tt>), second, | |
| the name of the environment variable to examine, and third, the optional | |
| <a href="#description">additional extra text</a> to emit when the | |
| <tt>--help</tt> option is invoked.<p> | |
| <tt>cl::ParseEnvironmentOptions</tt> will break the environment | |
| variable's value up into words and then process them using | |
| <a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>. | |
| <b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support | |
| quoting, so an environment variable containing <tt>-option "foo bar"</tt> will | |
| be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>, | |
| which is different from what you would get from the shell with the same | |
| input.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="cl::opt"><h4><hr size=0>The <tt>cl::opt</tt> class</h4><ul> | |
| The <tt>cl::opt</tt> class is the class used to represent scalar command line | |
| options, and is the one used most of the time. It is a templated class which | |
| can take up to three arguments (all except for the first have default values | |
| though):<p> | |
| <pre> | |
| <b>namespace</b> cl { | |
| <b>template</b> <<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>, | |
| <b>class</b> ParserClass = parser<DataType> > | |
| <b>class</b> opt; | |
| } | |
| </pre><p> | |
| The first template argument specifies what underlying data type the command line | |
| argument is, and is used to select a default parser implementation. The second | |
| template argument is used to specify whether the option should contain the | |
| storage for the option (the default) or whether external storage should be used | |
| to contain the value parsed for the option (see <a href="#storage">Internal vs | |
| External Storage</a> for more information).<p> | |
| The third template argument specifies which parser to use. The default value | |
| selects an instantiation of the <tt>parser</tt> class based on the underlying | |
| data type of the option. In general, this default works well for most | |
| applications, so this option is only used when using a <a | |
| href="#customparser">custom parser</a>.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="cl::list"><h4><hr size=0>The <tt>cl::list</tt> class</h4><ul> | |
| The <tt>cl::list</tt> class is the class used to represent a list of command | |
| line options. It too is a templated class which can take up to three | |
| arguments:<p> | |
| <pre> | |
| <b>namespace</b> cl { | |
| <b>template</b> <<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>, | |
| <b>class</b> ParserClass = parser<DataType> > | |
| <b>class</b> list; | |
| } | |
| </pre><p> | |
| This class works the exact same as the <a href="#cl::opt"><tt>cl::opt</tt></a> | |
| class, except that the second argument is the <b>type</b> of the external | |
| storage, not a boolean value. For this class, the marker type '<tt>bool</tt>' | |
| is used to indicate that internal storage should be used.<p> | |
| <!-- _______________________________________________________________________ --> | |
| </ul><a name="cl::alias"><h4><hr size=0>The <tt>cl::alias</tt> class</h4><ul> | |
| The <tt>cl::alias</tt> class is a nontemplated class that is used to form | |
| aliases for other arguments.<p> | |
| <pre> | |
| <b>namespace</b> cl { | |
| <b>class</b> alias; | |
| } | |
| </pre></p> | |
| The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be used | |
| to specify which option this is an alias for. Alias arguments default to being | |
| <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do the | |
| conversion from string to data.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0><tr><td> </td><td width="100%"> <font color="#EEEEFF" face="Georgia,Palatino"><b> | |
| <a name="builtinparsers">Builtin parsers | |
| </b></font></td></tr></table><ul> | |
| Parsers control how the string value taken from the command line is translated | |
| into a typed value, suitable for use in a C++ program. By default, the | |
| CommandLine library uses an instance of <tt>parser<type></tt> if the | |
| command line option specifies that it uses values of type '<tt>type</tt>'. | |
| Because of this, custom option processing is specified with specializations of | |
| the '<tt>parser</tt>' class.<p> | |
| The CommandLine library provides the following builtin parser specializations, | |
| which are sufficient for most applications. It can, however, also be extended to | |
| work with new data types and new ways of interpreting the same data. See the <a | |
| href="#customparser">Writing a Custom Parser</a> for more details on this type | |
| of library extension.<p> | |
| <li><a name="genericparser">The <b>generic <tt>parser<t></tt> parser</b> | |
| can be used to map strings values to any data type, through the use of the <a | |
| href="#cl::values">cl::values</a> property, which specifies the mapping | |
| information. The most common use of this parser is for parsing enum values, | |
| which allows you to use the CommandLine library for all of the error checking to | |
| make sure that only valid enum values are specified (as opposed to accepting | |
| arbitrary strings). Despite this, however, the generic parser class can be used | |
| for any data type.<p> | |
| <li><a name="boolparser">The <b><tt>parser<bool></tt> specialization</b> | |
| is used to convert boolean strings to a boolean value. Currently accepted | |
| strings are "<tt>true</tt>", "<tt>TRUE</tt>", "<tt>True</tt>", "<tt>1</tt>", | |
| "<tt>false</tt>", "<tt>FALSE</tt>", "<tt>False</tt>", and "<tt>0</tt>".<p> | |
| <li><a name="stringparser">The <b><tt>parser<string></tt> specialization</b> simply stores the parsed string into the string value specified. No conversion or modification of the data is performed.<p> | |
| <li><a name="intparser">The <b><tt>parser<int></tt> specialization</b> | |
| uses the C <tt>strtol</tt> function to parse the string input. As such, it will | |
| accept a decimal number (with an optional '+' or '-' prefix) which must start | |
| with a non-zero digit. It accepts octal numbers, which are identified with a | |
| '<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of | |
| '<tt>0x</tt>' or '<tt>0X</tt>'.<p> | |
| <li><a name="doubleparser">The <b><tt>parser<double></tt></b> and | |
| <b><tt>parser<float></tt> specializations</b> use the standard C | |
| <tt>strtod</tt> function to convert floating point strings into floating point | |
| values. As such, a broad range of string formats is supported, including | |
| exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales. | |
| <p> | |
| <!-- *********************************************************************** --> | |
| </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0><tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b> | |
| <a name="extensionguide">Extension Guide | |
| </b></font></td></tr></table><ul> | |
| <!-- *********************************************************************** --> | |
| Although the CommandLine library has a lot of functionality built into it | |
| already (as discussed previously), one of its true strengths lie in its | |
| extensibility. This section discusses how the CommandLine library works under | |
| the covers and illustrates how to do some simple, common, extensions.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> | |
| <tr><td> </td><td width="100%"> <font color="#EEEEFF" | |
| face="Georgia,Palatino"><b> <a name="customparser">Writing a custom parser | |
| </b></font></td></tr></table><ul> | |
| One of the simplest and most common extensions is the use of a custom parser. | |
| As <a href="#builtinparsers">discussed previously</a>, parsers are the portion | |
| of the CommandLine library that turns string input from the user into a | |
| particular parsed data type, validating the input in the process.<p> | |
| There are two ways to use a new parser:<p> | |
| <ol> | |
| <li>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for | |
| your custom data type.<p> | |
| This approach has the advantage that users of your custom data type will | |
| automatically use your custom parser whenever they define an option with a | |
| value type of your data type. The disadvantage of this approach is that it | |
| doesn't work if your fundemental data type is something that is already | |
| supported.<p> | |
| <li>Write an independent class, using it explicitly from options that need | |
| it.<p> | |
| This approach works well in situations where you would line to parse an | |
| option using special syntax for a not-very-special data-type. The drawback | |
| of this approach is that users of your parser have to be aware that they are | |
| using your parser, instead of the builtin ones.<p> | |
| </ol><p> | |
| To guide the discussion, we will discuss a custom parser that accepts file | |
| sizes, specified with an optional unit after the numeric size. For example, we | |
| would like to parse "102kb", "41M", "1G" into the appropriate integer value. In | |
| this case, the underlying data type we want to parse into is | |
| '<tt>unsigned</tt>'. We choose approach #2 above because we don't want to make | |
| this the default for all <tt>unsigned</tt> options.<p> | |
| To start out, we declare our new <tt>FileSizeParser</tt> class:<p> | |
| <pre> | |
| <b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser<<b>unsigned</b>> { | |
| <i>// parse - Return true on error.</i> | |
| <b>bool</b> parse(cl::Option &O, <b>const char</b> *ArgName, <b>const</b> std::string &ArgValue, | |
| <b>unsigned</b> &Val); | |
| }; | |
| </pre><p> | |
| Our new class inherits from the <tt>cl::basic_parser</tt> template class to fill | |
| in the default, boiler plate, code for us. We give it the data type that we | |
| parse into (the last argument to the <tt>parse</tt> method so that clients of | |
| our custom parser know what object type to pass in to the parse method (here we | |
| declare that we parse into '<tt>unsigned</tt>' variables.<p> | |
| For most purposes, the only method that must be implemented in a custom parser | |
| is the <tt>parse</tt> method. The <tt>parse</tt> method is called whenever the | |
| option is invoked, passing in the option itself, the option name, the string to | |
| parse, and a reference to a return value. If the string to parse is not well formed, the parser should output an error message and return true. Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In our example, we implement <tt>parse</tt> as:<p> | |
| <pre> | |
| <b>bool</b> FileSizeParser::parse(cl::Option &O, <b>const char</b> *ArgName, | |
| <b>const</b> std::string &Arg, <b>unsigned</b> &Val) { | |
| <b>const char</b> *ArgStart = Arg.c_str(); | |
| <b>char</b> *End; | |
| <i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i> | |
| Val = (unsigned)strtol(ArgStart, &End, 0); | |
| <b>while</b> (1) { | |
| <b>switch</b> (*End++) { | |
| <b>case</b> 0: <b>return</b> false; <i>// No error</i> | |
| <b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i> | |
| <b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i> | |
| <b>break</b>; | |
| <b>case</b> 'g': <b>case</b> 'G': Val *= 1024*1024*1024; <b>break</b>; | |
| <b>case</b> 'm': <b>case</b> 'M': Val *= 1024*1024; <b>break</b>; | |
| <b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>; | |
| default: | |
| <i>// Print an error message if unrecognized character!</i> | |
| <b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!"); | |
| } | |
| } | |
| } | |
| </pre><p> | |
| This function implements a very simple parser for the kinds of strings we are | |
| interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for | |
| example), it is good enough for this example. Note that we use the option | |
| itself to print out the error message (the <tt>error</tt> method always returns | |
| true) in order to get a nice error message (shown below). Now that we have our | |
| parser class, we can use it like this:<p> | |
| <pre> | |
| <b>static</b> <a href="#cl::opt">cl::opt</a><<b>unsigned</b>, <b>false</b>, FileSizeParser> | |
| MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>), | |
| <a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>")); | |
| </pre><p> | |
| Which adds this to the output of our program:<p> | |
| <pre> | |
| OPTIONS: | |
| -help - display available options (--help-hidden for more) | |
| ... | |
| <b>-max-file-size=<size> - Maximum file size to accept</b> | |
| </pre><p> | |
| And we can test that our parse works correctly now (the test program just prints | |
| out the max-file-size argument value):<p> | |
| <pre> | |
| $ ./test | |
| MFS: 0 | |
| $ ./test -max-file-size=123MB | |
| MFS: 128974848 | |
| $ ./test -max-file-size=3G | |
| MFS: 3221225472 | |
| $ ./test -max-file-size=dog | |
| -max-file-size option: 'dog' value invalid for file size argument! | |
| </pre><p> | |
| It looks like it works. The error message that we get is nice and helpful, and | |
| we seem to accept reasonable file sizes. This wraps up the "custom parser" | |
| tutorial.<p> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> | |
| <tr><td> </td><td width="100%"> <font color="#EEEEFF" | |
| face="Georgia,Palatino"><b> <a name="explotingexternal">Exploiting external | |
| storage </b></font></td></tr></table><ul> | |
| <!-- ======================================================================= --> | |
| </ul><table width="100%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> | |
| <tr><td> </td><td width="100%"> <font color="#EEEEFF" | |
| face="Georgia,Palatino"><b> <a name="dynamicopts">Dynamically adding command | |
| line options </b></font></td></tr></table><ul> | |
| <!-- *********************************************************************** --> | |
| </ul> | |
| <!-- *********************************************************************** --> | |
| <hr> | |
| <font size=-1> | |
| <address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address> | |
| <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a> | |
| <br> | |
| <!-- Created: Tue Jan 23 15:19:28 CST 2001 --> | |
| <!-- hhmts start --> | |
| Last modified: Fri Aug 1 16:30:11 CDT 2003 | |
| <!-- hhmts end --> | |
| </font> | |
| </body></html> |