includefile(header.inc)

COMMENT(manpage, section, releasedate, archive, short name)
manpage(FBB::Arg)(3bobcat)(_CurYrs_)(libbobcat1-dev__CurVers_-x.tar.gz)
                    (Command Line Arguments)

manpagename(FBB::Arg)(A singleton class interfacing command line arguments)

manpagesynopsis()
    bf(#include <bobcat/arg>)nl()
    Linking option: tt(-lbobcat) 

manpagedescription()
    Singleton class (see Gamma em(et al.), 1995) built around bf(getopt())(3)
and bf(getopt_long())(3). The class handles short- and long command-line
options,

includefile(namespace.inc)

manpagesection(INHERITS FROM)
    -

manpagesection(ENUMERATION)

    The bf(FBB::Arg::Type) enumeration is defined by the bf(FBB::Arg)
class. It has the following values intended for public use: bf(None, Required,
Optional). These values are used when constructing objects of the nested class
bf(FBB::Arg::LongOption), see below.

manpagesection(CONSTRUCTORS)
    Since the class is a em(Singleton), no public constructors are
available. Instead, static members are offered to initialize and access the
single bf(FBB::Arg) object. See below.

manpagesection(STATIC MEMBERS)
    itemization(
    itb(FBB::Arg &initialize(char const *optstring, int argc, char **argv))
        Initializes the bf(FBB::Arg) singleton. Must be called only once.
Throws an bf(FBB::Errno) exception if called repeatedly or if called with
tt(argv) not containing a defined option (which is shown by the
bf(FBB::Errno)'s tt(what()) member). Returns a reference to the singleton
object, allowing code initializing bf(Arg) to use the initialized object
immediately.
    itb(FBB::Arg &initialize(char const *optstring,
                                LongOption const * const begin,
                                LongOption const * const end,
                                int argc, char **argv))
        Initializes the bf(FBB::Arg) singleton. Accepts two iterators of an
array of bf(Arg::LongOption) objects, holding long-options. Must be called
only once. Throws an bf(FBB::Errno) exception if called repeatedly or if
called with tt(argv) not containing a defined option (which is shown by the
bf(FBB::Errno)'s tt(what()) member).  See the description of
bf(Arg::LongOption) below.  Returns a reference to the singleton object,
allowing code initializing bf(Arg) to use the initialized object immediately.

        tt(optstring) should consist of letters, possibly postfixed by:
        itemization(
        it() a colon (tt(:)), indicating that the option has a required
            argument;
        it() a double colon (tt(::)), indicating that the option itself 
            has an optional argument (in that case, the option's value 
            will be empty, unless specified).
        )

    itb(FBB::Arg &instance()) 
        Returns the instance of the bf(Arg) object, available after calling
one of the bf(Arg::initialize()) members.  If called before initialization, an
tt(FBB::Errno) exception is thrown.
    )

manpagesection(OVERLOADED OPERATOR)

    itemization(
    itb(char const *operator[](size_t idx) const)
        Returns tt(argument[idx]), after having removed all specified options.
0 is returned if no tt(arg[x]) is available.  The program name (tt(argv[0]))
is NOT counted here: index 0 refers to the first ARGUMENT, e.g., the program's
tt(argv[1]).
    )

manpagesection(NON-STATIC MEMBER FUNCTIONS)
    itemization(
    itb(std::string const &basename() const)
        Returns the program's basename.
    itb(size_t nArgs() const)
        Returns the number of arguments left after option-removal.  The
program name bf(argv[0]) is NOT counted here.
    itb(size_t nOptions() const)
        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.
    itb(size_t nLongOptions() const)
        Returns the number of long options for which no short option synonym
exist. If long options are multiply specified, then each specification is
counted. 
    itb(size_t option(int option) const)
        The number of times  `option' (or its long option synonym, if defined)
was specified is returned.
    itb(size_t option(std::string const &options) const)
        The number of times one of the options specified in the `option'
argument (or their long option synonyms) were present is returned.
    itb(size_t option(string *value, int option) const)
        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 tt(*value), which is left
untouched if `option' was not present. 0 may be specified for bf(value) if the
option does not have a value or if the value should not be stored.
    itb(size_t option(size_t idx, string *value, int option) const)
        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
tt(idx)th occurrence (0-based offset) of this option is stored in tt(*value),
which is left untouched if `option' was not present or if tt(idx) is or
exceeds the number of specifications of the provided option. 0 may be
specified for bf(value) if the option does not have a value or if the value
should not be stored. 
    itb(size_t option(size_t *idx, string *value, int option) const)
        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 tt(option) specifications) of the first option having a
non-empty option value is returned in tt(*idx), while its option value is
stored in tt(*value). Both tt(*value) and tt(*idx) are left untouched if
`option' was not present. 0 may be specified for bf(value) if the option does
not have a value or if the value should not be stored.
    itb(size_t option(string *value, char const *longOption) const)
        Returns the number of times the specified long option (not having a
single-character synonym) was present. Its value is then stored in tt(*value),
which is left untouched if the long option was not present. 0 may be specified
for bf(value) if the option does not have a value or if the value should not
be stored.
    itb(size_t option(size_t idx, string *value, 
                                        char const * longOption) const)
        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 tt(idx)th occurrence (0-based offset) of this long option is
stored in tt(*value), which is left untouched if the long option was not
present or if tt(idx) is or exceeds the number of specifications of the
provided long option. 0 may be specified for bf(value) if the long option does
not have a value or if the value should not be stored.
    itb(size_t option(size_t *idx, string *value, int longOption) const)
        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 tt(*idx), while its
option value is stored in tt(*value). Both tt(*value) and tt(*idx) are left
untouched if long option was not present. 0 may be specified for bf(value) if
the long option does not have a value or if the value should not be stored.
    itb(void versionHelp(void (*usage)(std::string const &progname), 
        char const *version, size_t minArgs, int helpFlag = 'h', 
        int versionFlag = 'v') const)
    If tt(versionFlag) was specified, and the tt(helpFlag) was not specified
the program's name (using bf(basename())) and tt(version) is displayed to
tt(std::cout). Otherwise, if the tt(helpFlag) was provided or if there are
fewer arguments than tt(minArgs) tt(usage()) is called with argument
bf(basename()). If either version- or help information is shown, the bf(int)
value 1 is thrown as an exception.

    The address of the tt(usage()) function, the current version and the
minimum number of arguments must be specified. Default argument values are
provided for the option flags.
    itb(char const **argPointers())
        Returns tt(argv)-like set of pointers to all remaining arguments. The
last element is guaranteed to be a 0-pointer. The first tt(nArg()) elements
point to the respective bf(C)-string values of the arguments.
    )

manpagesection(THE NESTED CLASS FBB::Arg::LongOption)
    Long options are defined using objects of the nested class
bf(FBB::Arg::LongOption). This class offers the following constructors:
    itemization(
    itb(FBB::Arg::LongOption(char const *name, FBB::Arg::Type type = None))
        This constructor is used to define a long option for which no
corresponding short option is defined. The parameter tt(name) is the name of
the long option (without prefixing the tt(--) characters, which em(are)
required when specifying the long option). 
    itb(FBB::Arg::LongOption(char const *name, int optionChar))
        This constructor is used to define a long option for which a
corresponding short option is defined. The parameter tt(name) is the name of
the long option (without prefixing the tt(--) characters, which em(are)
required when specifying the long option). 
    )
    In a program, long options may be specified as follows:
    itemization(
    it() First, construct an array 
        verb(
    FBB::Arg::LongOption longOptions[] = { c1, c2, ... cn }
        )
    Where tt(c1, c2, ..., cn) are bf(n) constructor invocations of 
            bf(FBB::Arg::LongOption()) constructors
    it() Next, pass bf(longOptions, LongOptions + n)
                as 2nd and 3rd arguments to bf(initialize())
    )

manpagesection(EXAMPLE)
    The following example illustrates defining long options and shows an
initialization. It is not a full-fletched example in the sense of a small 
runnable program.
        verb(
    #include <bobcat/arg>

    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'),
        };
    
        Arg::LongOption const *const longEnd = 
                        longOptions + 
                        sizeof(longOptions) / sizeof(Arg::LongOption); 
    }
    
    int main(int argc, char **argv)
    try
    {
        Arg &arg = Arg::initialize("df:hv", 
                        longOptions, longEnd, argc, argv);

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

manpagefiles()
    em(bobcat/arg) - defines the class interface

manpageseealso()
    bf(bobcat)(7)

manpagebugs()
    None Reported.

includefile(trailer.inc)