An alternative to getopt() and getopt_long() (and boost::program_options) by using of callback functions for each recognized option in the shape of:
- classical function-pointers
- anonymous "lambda" functions
- or virtual object-functions
- Avoiding of global variables like "optind" or "optarg".
- Using of a callback function for each option instead of (confusing huge) switch-case- or if-statements. (Avoiding of spaghetti-code.)
- Use of anonymous callback functions (lambda functions) possible. That means implementation of the function body directly in the option-list initializer possible. (See code-example below.)
- Object oriented flavor: Short option-name (if given), long option-name (if given) and help-text (if given) are bound together in a single object by a corresponding callback function.
- Avoiding of redundance: If you'll change a option name, so you have to do this on one place in your source-code only.
- Commands by mixed order of options and non-options are possible.
- Specialized callback objects per single option and/or initializer-lists with callback lambda- functions and/or function-pointers are possible. (This is a matter of taste.)
- Scalable, if a serten kind of option-type won't used for your project just define the corresponding compiler-switch (CONFIG_CLOP_NO_...) in your Makefile respectively build-system to reduce memory, provided you'll link the source-code directly to your project rather than the shared-library.
If you intend to write a pure C-project or you are not allowed to write your program in C++ (not to mention in C++11), so you can take a look in the following link:
https://github.com/UlrichBecker/command_line_option_parser
A practical application using this module you can find in this repository: https://github.com/UlrichBecker/DocFsm
Excuses my Eric Allman coding-style and my bad English ;-)
Example for using lambda callback function in a initializer-list:
See also ./example/lambda/cmd_opt_lambda.cpp
#include <parse_opts.hpp>
using namespace std;
using namespace CLOP; // Namespace for Command-Line-Option-Parser
int main( int argc, char** ppArgv )
{
// Initializer-list
vector<OPTION> optList =
{
{
OPT_LAMBDA( parser,
{
cout << "Usage: " << parser->getProgramName() << " [options,...]\n";
parser->list( cout );
cout << endl;
exit( EXIT_SUCCESS );
return 0;
}),
.m_hasArg = OPTION::NO_ARG,
.m_id = 0,
.m_shortOpt = 'h',
.m_longOpt = "help",
.m_helpText = "Print this help and exit"
},
{
//... further options ...
}
};
PARSER parser( argc, ppArgv, optList );
for( int i = 1; i < argc; i++ )
{
i = parser( i );
if( i < 0 )
return EXIT_FAILURE;
if( i < argc )
cout << "Non option argument on index " << i << ": " << ppArgv[i] << endl;
}
// Do something others...
return EXIT_SUCCESS;
}Example for using virtual object-functions for each option:
See also ./example/objects/cmd_opt_objects.cpp
#include <parse_opts.hpp>
using namespace std;
using namespace CLOP; // Namespace for Command-Line-Option-Parser
class OPTION_HELP: public OPTION_V
{
public:
OPTION_HELP( void )
{
m_hasArg = NO_ARG;
m_shortOpt = 'h';
m_longOpt = "help";
m_helpText = "Print this help and exit.";
}
private:
// Function becomes immediately triggered if the parser recognized
// the option "-h" or "--help" in the commend-line.
int onGiven( PARSER* poParser ) override
{
cout << "Usage: " << poParser->getProgramName() << " [options,...]\n";
poParser->list( cout );
cout << endl;
exit( EXIT_SUCCESS );
return 0;
}
};
// Further classes inherited of the base-class CLOP::OPTION_V ...
class MY_PARSER: public PARSER
{
public:
MY_PARSER( int argc, char** ppArgv ):
PARSER( argc, ppArgv ) {}
// The overwriting of the following callback-function makes it enable
// to evaluate non-option arguments too.
int onArgument( void ) override
{
cout << "Non option argument on index " << getArgIndex() << ": "
<< getArgVect()[getArgIndex()] << endl;
return 1; // Continue parsing for mixed order.
}
};
int main( int argc, char** ppArgv )
{
MY_PARSER parser( argc, ppArgv );
OPTION_HELP optHelp;
// ... further objects of the base CLOP::OPTION_V
if( parser( optHelp )() < 0 )
return EXIT_FAILURE;
// Do something others ...
return EXIT_SUCCESS;
}