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¶
- o
- 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.
- 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, 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:
- o
- a colon (:), indicating that the option requires an option
value.
- o
- 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.
- o
- 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¶
- o
- 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¶
- 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 C-string values of the
arguments.
- 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
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
- 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 for which no short option synonym exist.
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 counted.
- o
- size_t option(int option) const:
The number of times `option’ (or its long option synonym, if defined)
was specified is returned.
- o
- 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.
- 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. 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 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.
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:
- o
- 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).
- 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
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¶
- o
- bobcat_3.23.01-x.dsc: detached signature;
- o
- bobcat_3.23.01-x.tar.gz: source archive;
- o
- bobcat_3.23.01-x_i386.changes: change log;
- o
- libbobcat1_3.23.01-x_*.deb: debian package holding the
libraries;
- o
- libbobcat1-dev_3.23.01-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).