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<h1 id="title">FBB::Arg(3bobcat)</h1>
<h2 id="author">Command Line Arguments<br/>(libbobcat-dev_4.08.02-x.tar.gz)</h2>
<h2 id="date">2005-2017</h2>


<p>
<h2 >NAME</h2>FBB::Arg - A singleton class interfacing command line arguments
<p>
<h2 >SYNOPSIS</h2>
    <strong >#include &lt;bobcat/arg&gt;</strong><br/>
    Linking option: <em >-lbobcat</em> 
<p>
<h2 >DESCRIPTION</h2>
    Singleton class (see Gamma <em >et al.</em>, 1995) built around <strong >getopt()</strong>(3)
and <strong >getopt_long()</strong>(3). The class handles short- and long command-line
options,
<p>
<h2 >NAMESPACE</h2>
    <strong >FBB</strong><br/>
    All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace <strong >FBB</strong>.
<p>
<h2 >INHERITS FROM</h2>
    -
<p>
<h2 >ENUMERATION</h2>
<p>
The <strong >FBB::Arg::Type</strong> enumeration is defined by the <strong >FBB::Arg</strong>
class. It has the following values intended for public use: <strong >None, Required,
Optional</strong>. These values are used when constructing objects of the nested class
<strong >FBB::Arg::LongOption</strong>, see below.
<p>
<h2 >CONSTRUCTORS</h2>
    Since the class is a <em >Singleton</em>, no public constructors are
available. Instead, static members are offered to initialize and access the
single <strong >FBB::Arg</strong> object. See below.
<p>
<h2 >STATIC MEMBERS</h2>
    <ul>
    <li> <strong >FBB::Arg &amp;initialize(char const *optstring, int argc, char **argv)</strong>:<br/>
        Initializes the <strong >FBB::Arg</strong> singleton. Must be called only once.
Throws an <strong >FBB::Exception</strong> exception if called repeatedly or if called with
<em >argv</em> not containing a defined option (which is shown by the
<strong >FBB::Exception</strong>'s <em >what()</em> member). Returns a reference to the singleton
object, allowing code initializing <strong >Arg</strong> to use the initialized object
immediately.
    <li> <strong >FBB::Arg &amp;initialize(char const *optstring,
                                LongOption const * const begin,
                                LongOption const * const end,
                                int argc, char **argv)</strong>:<br/>
       Initializes the <strong >FBB::Arg</strong> singleton. Accepts two iterators of an
        array of <strong >Arg::LongOption</strong> objects, holding long-options. Must be
        called only once. Throws an <strong >FBB::Exception</strong> exception if called
        repeatedly or if called with <em >argv</em> not containing a defined option
        (which is shown by the <strong >FBB::Exception</strong>'s <em >what()</em> member).  See the
        description of <strong >Arg::LongOption</strong> below.  Returns a reference to the
        singleton object, allowing code initializing <strong >Arg</strong> to use the
        initialized object immediately.
<p>
<em >optstring</em> should consist of letters, possibly postfixed by:
        <ul>
        <li> a colon (<em >:</em>), indicating that the option requires an option
            value. 
        <li> a double colon (<em >::</em>), indicating that the option itself has an
            optional argument. With short options the option value is
            considered absent unless it immediately follows the short option
            (e.g., <em >-tvalue</em> for a short option <em >-t</em>). Long options
            optionally accepting arguments should always immediately be
            followed by a = character. Here the option's value must
            immediately follow the = character, and must start with a
            non-blank character, or the option's value is considered
            absent. E.g., <em >--value=</em> indicates an absent option value,
            <em >--value=text</em> indicates the option's value equals <em >text</em>.  If
            an option value itself contains blanks, it should be surrounded by
            single or double quotes (e.g., <em >-t'this value'</em>, or
            <em >--text='this value'</em>). The surrounding quotes themselves are
            not part of the option's value.            
        </ul>
<p>
<li> <strong >FBB::Arg &amp;instance()</strong>:<br/> 
       Returns the instance of the <strong >Arg</strong> object, available after calling one
        of the <strong >Arg::initialize()</strong> members.  If called before
        initialization, an <em >FBB::Exception</em> exception is thrown.
    </ul>
<p>
<h2 >OVERLOADED OPERATOR</h2>
<p>
<ul>
    <li> <strong >char const *operator[](size_t idx) const</strong>:<br/>
       Returns <em >argument[idx]</em>, after having removed all specified options.
        0 is returned if no <em >arg[x]</em> is available.  The program name
        (<em >argv[0]</em>) is NOT counted here: index 0 refers to the first
        ARGUMENT, e.g., the program's <em >argv[1]</em>.
    </ul>
<p>
<h2 >NON-STATIC MEMBER FUNCTIONS</h2>
    <ul>
    <li> <strong >char const **argPointers()</strong>:<br/>
       Returns <em >argv</em>-like set of pointers to all remaining arguments. The
        last element is guaranteed to be a 0-pointer. The first <em >nArg()</em>
        elements point to the respective <strong >C</strong>-string values of the arguments.
    <li> <strong >std::string const &amp;basename() const</strong>:<br/>
        Returns the program's basename.
    <li> <strong >size_t beyondDashes() const</strong>:<br/>
       Returns the index of the first argument after a <em >--</em>
        argument or <em >nArgs()</em> if no <em >--</em> argument was encountered.<br/> 
       A <em >--</em> argument ends <em >Arg</em>'s argument processing, and all arguments
        beyond the first <em >--</em> argument are kept `as is'. The
        <em >beyondDashes</em> member returns the index of the first argument beyond
        the <em >--</em> argument, which itself is removed from the remaining set of
        arguments.
    <li> <strong >void help() const</strong>:<br/>
       If the member <em >versionHelp</em> (see below) has been called then this
        member calls the <em >usage</em> function that was passed to
        <em >versionHelp</em>. If <em >versionHelp</em> has not been called (i.e., if no
        <em >usage</em> function has been specified) then an exception is thrown.
    <li> <strong >size_t nArgs() const</strong>:<br/>
       Returns the number of arguments left after option-removal.  The
        program name <strong >argv[0]</strong> is NOT counted here.
    <li> <strong >size_t nLongOptions() const</strong>:<br/> 
       Returns the number of long options for which no short option synonym
        exist. If long options are multiply specified, then each specification
        is counted.
    <li> <strong >size_t nOptions() const</strong>:<br/>
       Returns the number of specified single character options. If short
        options have long option synonyms, then these long option synonyms are
        counted as if they were specified as single character options. If
        single character options (or their long option synonyms) are multiply
        specified, then each specification is counted.
    <li> <strong >size_t option(int option) const</strong>:<br/>
       The number of times `option' (or its long option synonym, if defined)
        was specified is returned.
    <li> <strong >size_t option(std::string const &amp;options) const</strong>:<br/>
       The number of times one of the options specified in the `option'
        argument (or their long option synonyms) were present is returned.
    <li> <strong >size_t option(string *value, int option) const</strong>:<br/>
       Returns the number of times the provided option (or its long option
        synonym) was present. If the return value is non-zero then the value
        of the first occurrence of this option is stored in <em >*value</em>, which
        is left untouched if `option' was not present. 0 may be specified for
        <strong >value</strong> if the option does not have a value or if the value should
        not be stored.
    <li> <strong >size_t option(size_t idx, string *value, int option) const</strong>:<br/>
       Returns the number of times the provided option (or its long option
        synonym) was present. If the return value is non-zero then the value
        of the <em >idx</em>th occurrence (0-based offset) of this option is stored
        in <em >*value</em>, which is left untouched if `option' was not present or
        if <em >idx</em> is or exceeds the number of specifications of the provided
        option. 0 may be specified for <strong >value</strong> if the option does not have a
        value or if the value should not be stored.
    <li> <strong >size_t option(size_t *idx, string *value, int option) const</strong>:<br/>
       Returns the number of times the provided option (or its long option
        synonym) was present. If the return value is non-zero then the offset
        (within the series of <em >option</em> specifications) of the first option
        having a non-empty option value is returned in <em >*idx</em>, while its
        option value is stored in <em >*value</em>. Both <em >*value</em> and <em >*idx</em> are
        left untouched if `option' was not present. 0 may be specified for
        <strong >value</strong> if the option does not have a value or if the value should
        not be stored.
    <li> <strong >size_t option(string *value, char const *longOption) const</strong>:<br/>
       Returns the number of times the specified long option (not having a
        single-character synonym) was present. Its value is then stored in
        <em >*value</em>, which is left untouched if the long option was not
        present. 0 may be specified for <strong >value</strong> if the option does not have
        a value or if the value should not be stored.
    <li> <strong >size_t option(size_t idx, string *value, 
                                        char const * longOption) const</strong>:<br/>
       Returns the number of times the provided long option (not having a
        single-character synonym) was present. If the return value is non-zero
        then the value of the <em >idx</em>th occurrence (0-based offset) of this
        long option is stored in <em >*value</em>, which is left untouched if the
        long option was not present or if <em >idx</em> is or exceeds the number of
        specifications of the provided long option. 0 may be specified for
        <strong >value</strong> if the long option does not have a value or if the value
        should not be stored.
    <li> <strong >size_t option(size_t *idx, string *value, int longOption) const</strong>:<br/>
       Returns the number of times the provided long option (not having a
        single-character synonym) was present. If the return value is non-zero
        then the offset (within the series of this long option specifications)
        of the first long option having a non-empty option value is returned
        in <em >*idx</em>, while its option value is stored in <em >*value</em>. Both
        <em >*value</em> and <em >*idx</em> are left untouched if long option was not
        present. 0 may be specified for <strong >value</strong> if the long option does not
        have a value or if the value should not be stored.
    <li> <strong >void versionHelp(void (*usage)(std::string const &amp;progname), 
        char const *version, size_t minArgs, int helpFlag = 'h', 
        int versionFlag = 'v') const</strong>:<br/>
       If <em >versionFlag</em> was specified, and the <em >helpFlag</em> was not
        specified the program's name (using <strong >basename()</strong>) and <em >version</em> is
        displayed to <em >std::cout</em>. Otherwise, if the <em >helpFlag</em> was
        provided or if there are fewer arguments than <em >minArgs</em> <em >usage()</em>
        is called with argument <strong >basename()</strong>. If either version- or help
        information is shown, the <strong >int</strong> value 1 is thrown as an
        exception.<br/> 
       Note that <em >versionhelp</em> compares <em >minArgs</em> against <em >nArgs</em>. If
        <em >minArgs</em> should be compaired against the number of arguments up to
        a possible `--' argument (i.e., <em >beyondDashes</em>' return value), then
        add <em >nArgs() - beyondDashes()</em> to the <em >minArg</em> argument. E.g.,
            <pre>

    arg.versionHelp(usage, version, 2 + arg.nArgs() - arg.beyondDashes());
            
</pre>

       The address of the <em >usage()</em> function, the current version and the
        minimum number of arguments must be specified. Default argument values
        are provided for the option flags.
    </ul>
<p>
<h2 >THE NESTED CLASS FBB::Arg::LongOption</h2>
    Long options are defined using objects of the nested class
<strong >FBB::Arg::LongOption</strong>. This class offers the following constructors:
    <ul>
    <li> <strong >FBB::Arg::LongOption(char const *name, FBB::Arg::Type type = None)</strong>:<br/>
       This constructor is used to define a long option for which no
        corresponding short option is defined. The parameter <em >name</em> is the
        name of the long option (without prefixing the <em >--</em> characters,
        which <em >are</em> required when specifying the long option).
    <li> <strong >FBB::Arg::LongOption(char const *name, int optionChar)</strong>:<br/>
       This constructor is used to define a long option for which a
        corresponding short option is defined. The parameter <em >name</em> is the
        name of the long option (without prefixing the <em >--</em> characters,
        which <em >are</em> required when specifying the long option).
    </ul>
    In a program, long options may be specified as follows:
    <ul>
    <li> First, construct an array 
        <pre>

    FBB::Arg::LongOption longOptions[] = { c1, c2, ... cn }
        
</pre>

    Where <em >c1, c2, ..., cn</em> are <strong >n</strong> constructor invocations of 
            <strong >FBB::Arg::LongOption()</strong> constructors
    <li> Next, pass <strong >longOptions, LongOptions + n</strong>
                as 2nd and 3rd arguments to <strong >initialize()</strong>
    </ul>
<p>
<h2 >EXAMPLE</h2>
    The following example illustrates defining long options and shows an
initialization. It is not a full-fledched example in the sense of a small 
runnable program.
        <pre>

#include &lt;bobcat/arg&gt;

using namespace FBB;

namespace   // the anonymous namespace can be used here
{
    Arg::LongOption longOptions[] = 
    {
        Arg::LongOption{"debug"},
        Arg::LongOption{"filenames", 'f'},
        Arg::LongOption{"help", 'h'},
        Arg::LongOption{"version", 'v'},
    };
    auto longEnd = longOptions + sizeof(longOptions) / sizeof(longOptions[0]);
}

int main(int argc, char **argv)
try
{
    Arg &amp;arg = Arg::initialize("df:hv", 
                    longOptions, longEnd, argc, argv);

    // code using arg, etc.
}
catch(Exception const &amp;err)     // handle exceptions
{
    cerr &lt;&lt; err.what() &lt;&lt; endl;
    return err.which();
}
catch(int x)
{
    return x;
}
    
</pre>

<p>
<h2 >FILES</h2>
    <em >bobcat/arg</em> - defines the class interface
<p>
<h2 >SEE ALSO</h2>
    <strong >bobcat</strong>(7)
<p>
<h2 >BUGS</h2>
    None Reported.
<p>

<h2 >DISTRIBUTION FILES</h2>
    <ul>
    <li> <em >bobcat_4.08.02-x.dsc</em>: detached signature;
    <li> <em >bobcat_4.08.02-x.tar.gz</em>: source archive;
    <li> <em >bobcat_4.08.02-x_i386.changes</em>: change log;
    <li> <em >libbobcat1_4.08.02-x_*.deb</em>: debian package holding the
            libraries;
    <li> <em >libbobcat1-dev_4.08.02-x_*.deb</em>: debian package holding the
            libraries, headers and manual pages;
    <li> <em >http://sourceforge.net/projects/bobcat</em>: public archive location;
    </ul>
<p>
<h2 >BOBCAT</h2>
    Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
<p>
<h2 >COPYRIGHT</h2>
    This is free software, distributed under the terms of the 
    GNU General Public License (GPL).
<p>
<h2 >AUTHOR</h2>
    Frank B. Brokken (<strong >f.b.brokken@rug.nl</strong>).
<p>
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libbobcat-dev 4.08.02-2build1 / usr / share / doc / libbobcat4-dev / man / arg.3.html
