Provided by: libbobcat-dev_5.02.00-1build1_amd64 
NAME
FBB::Arg - A singleton class interfacing command line arguments
SYNOPSIS
#include <bobcat/arg>
Linking option: -lbobcat
DESCRIPTION
Singleton class (see Gamma et al., 1995) built around getopt()(3) and getopt_long()(3).
The class handles short- and long command-line options,
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are
defined in the namespace FBB.
INHERITS FROM
-
ENUMERATION
The FBB::Arg::Type enumeration is defined by the FBB::Arg class. It is used to specify
whether or not long options require arguments. It defines the following values: None,
Required, Optional.
o None: the long option does not use an argument;
o Required: the long option requires an argument value;
o Optional: the long option may optionally be provided with an argument value;
These values are used when constructing objects of the following (nested) class
FBB::Arg::LongOption.
THE NESTED CLASS FBB::Arg::LongOption
Long options are defined using objects of the nested class FBB::Arg::LongOption. This
class provides the following constructors:
o FBB::Arg::LongOption(char const *name, FBB::Arg::Type type = FBB::Arg::None):
This constructor is used to define a long option for which no corresponding short
option is defined. The parameter name is the name of the long option (without
prefixing the -- characters, which are required when specifying the long option).
o 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 name is the name of the long option (without
prefixing the -- characters, which are required when specifying the long option).
In a program, long options may be specified as follows:
o First, construct an array
FBB::Arg::LongOption longOptions[] = { c1, c2, ... cn };
Where c1, c2, ..., cn are n constructor invocations of FBB::Arg::LongOption()
constructors
o Next, pass longOptions, LongOptions + n as 2nd and 3rd arguments to Arg’s member
initialize()
CONSTRUCTORS
Since the class is a Singleton there are no public constructors. Instead, static members
are offered for initializing and accessing the single FBB::Arg object.
STATIC MEMBERS
o FBB::Arg &initialize(char const *optstring, int argc, char **argv):
Initializes the FBB::Arg singleton. May be called only once. Throws an
FBB::Exception exception if called repeatedly or if called with argv containing an
undefined option. If so, the Exception object’s what() member provides details. A
reference to the singleton object is returned.
o FBB::Arg &initialize(char const *optstring, LongOption const *const begin,
LongOption const *const end, int argc, char **argv):
Initializes the FBB::Arg singleton. Accepts two iterators of an array of
Arg::LongOption objects. May be called only once. Throws an FBB::Exception
exception if called repeatedly or if called with argv containing a undefined
option. If so, the Exception object’s what() member provides details. See the
description of Arg::LongOption below. A reference to the singleton object is
returned.
The parameter optstring must point to a null-terminated byte string (NTBS)
containing option characters, possibly postfixed by:
o a colon (:), indicating that the option requires an option value.
o a double colon (::), indicating that the option has an optional argument. With
short options the option value is considered absent unless it it directly attached
to the short option (e.g., -tvalue). Long options optionally accepting arguments
should always immediately be followed by an assignment character (=). Here the
option’s value must immediately follow the = character, and must start with a
non-blank character. E.g., --value= indicates an absent option value, --value=text
indicates the option’s value equals text. If an option value itself contains
blanks, it must be surrounded by single or double quotes (e.g., -t’this value’, or
--text=’this value’). The surrounding quotes are not part of the option’s value.
o FBB::Arg &instance():
Returns a reference to the iitialized Arg object. If called before initialization,
an FBB::Exception exception is thrown.
OVERLOADED OPERATOR
o char const *operator[](size_t idx) const:
Returns argument[idx], after having removed all specified options. It returns 0 if
no arg[x] is available. The program’s name (argv[0]) is NOT counted here: index 0
refers to the first ARGUMENT, e.g., the program’s argv[1].
NON-STATIC MEMBER FUNCTIONS
o char const **argPointers():
Returns argv-like set of pointers to all remaining arguments. The last element is
guaranteed to be a 0-pointer. The first nArg() elements point to the respective
values of the NTBS arguments that were passed to the program.
o std::string const &basename() const:
Returns the program’s basename.
o size_t beyondDashes() const:
Returns the index of the first argument after a -- argument or returns nArgs() if
no -- argument was encountered.
A -- argument ends Arg’s argument processing, and all arguments beyond the first --
argument are kept `as is’. The beyondDashes member returns the index of the first
argument beyond the -- argument, which itself is removed from the remaining set of
arguments.
o void help() const:
If the member versionHelp (see below) has been called then this member calls the
usage function that was passed to versionHelp. If versionHelp has not been called
(i.e., if no usage function has been specified) an FBB::Exception is thrown.
o size_t nArgs() const:
Returns the number of arguments left after option-removal. The program name
argv[0] is NOT counted here.
o size_t nLongOptions() const:
Returns the number of long options not having short option synonyms If long options
are multiply specified, then each specification is counted.
o 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 separately
counted.
o size_t option(int option) const:
Returns the number of times `option’ was specified (or its long option synonym, if
defined).
o size_t option(std::string const &options) const:
Returns the number of times each of the options specified in the `option’ argument
were specified (or their long option synonyms). Note that each character in options
must specify a single-character option.
o 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 *value, which is left untouched if `option’ was not
present. The parameter value may be initialized to 0 if the option does not have a
value or if the option’s value should not be stored.
o 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 idxth occurrence
(0-based offset) of this option is stored in *value, which is left untouched if
`option’ was not present or if idx is or exceeds the number of specifications of
the provided option. 0 may be specified for value if the option does not have a
value or if the value should not be stored.
o 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
option specifications) of the first option having a non-empty option value is
returned in *idx, while its option value is stored in *value. Both *value and *idx
are left untouched if `option’ was not present. 0 may be specified for value if the
option does not have a value or if the value should not be stored.
o 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 *value, which is
left untouched if the long option was not present. 0 may be specified for value if
the option does not have a value or if the value should not be stored.
o 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 idxth
occurrence (0-based offset) of this long option is stored in *value, which is left
untouched if the long option was not present or if idx is or exceeds the number of
specifications of the provided long option. 0 may be specified for value if the
long option does not have a value or if the value should not be stored.
o 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 *idx, while its option value is stored in
*value. Both *value and *idx are left untouched if long option was not present. 0
may be specified for value if the long option does not have a value or if the value
should not be stored.
o void versionHelp(void (*usage)(std::string const &progname), char const *version,
size_t minArgs, int helpFlag = ’h’, int versionFlag = ’v’) const:
If versionFlag was specified, and the helpFlag was not specified the program’s name
(using basename()) and version is displayed to std::cout. Otherwise, if the
helpFlag was provided or if there are fewer arguments than minArgs usage() is
called with argument basename(). If either version- or help information is shown,
the int value 1 is thrown as an exception.
Note that versionhelp compares minArgs against nArgs. If minArgs should be
compaired against the number of arguments up to a possible `--’ argument (i.e.,
beyondDashes’ return value), then add nArgs() - beyondDashes() to the minArg
argument. E.g.,
arg.versionHelp(usage, version, 2 + arg.nArgs()
- arg.beyondDashes());
The address of the usage() function, the current version and the minimum number of
arguments must be specified. Default argument values are provided for the option
flags.
EXAMPLE
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.
#include <bobcat/arg>
using namespace FBB;
using namespace std;
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 + size(longOptions);
}
int main(int argc, char **argv)
try
{
Arg &arg = Arg::initialize("df:hv",
longOptions, longEnd,
argc, argv);
// code using arg, etc.
}
catch (exception const &err) // handle exceptions
{
cerr << err.what() << ’\n’;
return 1;
}
FILES
bobcat/arg - defines the class interface
SEE ALSO
bobcat(7)
BUGS
None Reported.
DISTRIBUTION FILES
o bobcat_5.02.00-x.dsc: detached signature;
o bobcat_5.02.00-x.tar.gz: source archive;
o bobcat_5.02.00-x_i386.changes: change log;
o libbobcat1_5.02.00-x_*.deb: debian package holding the libraries;
o libbobcat1-dev_5.02.00-x_*.deb: debian package holding the libraries, headers and
manual pages;
o http://sourceforge.net/projects/bobcat: public archive location;
BOBCAT
Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.
COPYRIGHT
This is free software, distributed under the terms of the GNU General Public License
(GPL).
AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl).