libbobcat-dev_3.23.01-x.tar.gz Command Line Arguments
2005-2014
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 has the following values intended for public use: None, Required,
Optional. These values are used when constructing objects of the nested class
FBB::Arg::LongOption, see below.
CONSTRUCTORS
Since the class is a Singleton, no public constructors are
available. Instead, static members are offered to initialize and access the
single FBB::Arg object. See below.
STATIC MEMBERS
FBB::Arg &initialize(char const *optstring, int argc, char **argv):
Initializes the FBB::Arg singleton. Must be called only once.
Throws an FBB::Exception exception if called repeatedly or if called with
argv not containing a defined option (which is shown by the
FBB::Exception's what() member). Returns a reference to the singleton
object, allowing code initializing Arg to use the initialized object
immediately.
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, holding long-options. Must be
called only once. Throws an FBB::Exception exception if called
repeatedly or if called with argv not containing a defined option
(which is shown by the FBB::Exception's what() member). See the
description of Arg::LongOption below. Returns a reference to the
singleton object, allowing code initializing Arg to use the
initialized object immediately.
optstring should consist of letters, possibly postfixed by:
a colon (:), indicating that the option requires an option
value.
a double colon (::), 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., -tvalue for a short option -t). 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., --value= indicates an absent option value,
--value=text indicates the option's value equals text. If
an option value itself contains blanks, it should be surrounded by
single or double quotes (e.g., -t'this value', or
--text='this value'). The surrounding quotes themselves are
not part of the option's value.
FBB::Arg &instance():
Returns the instance of the Arg object, available after calling one
of the Arg::initialize() members. If called before
initialization, an FBB::Exception exception is thrown.
OVERLOADED OPERATOR
char const *operator[](size_t idx) const:
Returns argument[idx], after having removed all specified options.
0 is returned if no arg[x] is available. The program 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
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 C-string values of the arguments.
std::string const &basename() const:
Returns the program's basename.
size_t beyondDashes() const:
Returns the index of the first argument after a --
argument or 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.
size_t nArgs() const:
Returns the number of arguments left after option-removal. The
program name argv[0] is NOT counted here.
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.
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.
size_t option(int option) const:
The number of times `option' (or its long option synonym, if defined)
was specified is returned.
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.
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. 0 may be specified for
value if the option does not have a value or if the value should
not be stored.
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.
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.
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.
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.
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.
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 minArgsusage()
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.,
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.
THE NESTED CLASS FBB::Arg::LongOption
Long options are defined using objects of the nested class
FBB::Arg::LongOption. This class offers the following constructors:
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 name is the
name of the long option (without prefixing the -- characters,
which are required when specifying the long option).
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:
Where c1, c2, ..., cn are n constructor invocations of
FBB::Arg::LongOption() constructors
Next, pass longOptions, LongOptions + n
as 2nd and 3rd arguments to initialize()
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;
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 &arg = Arg::initialize("df:hv",
longOptions, longEnd, argc, argv);
// code using arg, etc.
}
catch(Exception const &err) // handle exceptions
{
cerr << err.what() << endl;
return err.which();
}
catch(int x)
{
return x;
}
FILES
bobcat/arg - defines the class interface
SEE ALSO
bobcat(7)
BUGS
None Reported.
DISTRIBUTION FILES
bobcat_3.23.01-x.dsc: detached signature;
bobcat_3.23.01-x.tar.gz: source archive;
bobcat_3.23.01-x_i386.changes: change log;
libbobcat1_3.23.01-x_*.deb: debian package holding the
libraries;
libbobcat1-dev_3.23.01-x_*.deb: debian package holding the
libraries, headers and manual pages;
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).