Display a custom help message in TCLAP - c++

Question

I'm using the TCLAP library to do some command line argument parsing. It's pretty great: except for the help messages it prints. Those are kind of ugly.
For instance, this is the output:
USAGE:
./a.out [-r] -n <string> [--] [--version] [-h]
Where:
-r, --reverse
Print name backwards
-n <string>, --name <string>
(required) Name to print
--, --ignore_rest
Ignores the rest of the labeled arguments following this flag.
--version
Displays version information and exits.
-h, --help
Displays usage information and exits.
Command description message
of this program:
#include <string>
#include <iostream>
#include <algorithm>
#include <tclap/CmdLine.h>
int main(int argc, char** argv){
try {
TCLAP::CmdLine cmd("Command description message", ' ', "0.9");
TCLAP::ValueArg<std::string> nameArg("n","name","Name to print",true,"homer","string");
cmd.add( nameArg );
TCLAP::SwitchArg reverseSwitch("r","reverse","Print name backwards", cmd, false);
cmd.parse( argc, argv );
std::string name = nameArg.getValue();
bool reverseName = reverseSwitch.getValue();
if ( reverseName ){
std::reverse(name.begin(),name.end());
std::cout << "My name (spelled backwards) is: " << name << std::endl;
} else{
std::cout << "My name is: " << name << std::endl;
}
} catch (TCLAP::ArgException &e) {
std::cerr << "error: " << e.error() << " for arg " << e.argId() << std::endl;
}
}
when run with ./a.out -h.
I want more creative control: I want to make my very own help message!
How can I achieve that?

Answer 1

The TCLAP::CmdLineOutput class is the one responsible for printing help (or usage) messages.
If you want TCLAP to print a custom message, you must first derive from the class mentioned above and add its instance to your TCLAP::CmdLine object like:
cmd.setOutput(new CustomHelpOutput());
Here is an example of a custom TCLAP::CmdLineOutput:
class CustomHelpOutput : public TCLAP::StdOutput {
public:
virtual void usage(TCLAP::CmdLineInterface& _cmd) override {
std::cout << "My program is called " << _cmd.getProgramName() << std::endl;
}
};
Note that you are the one responsible for cleaning up after your custom object, because TCLAP has a flag that disables its deletion in the setter.
inline void CmdLine::setOutput(CmdLineOutput* co)
{
if ( !_userSetOutput )
delete _output;
_userSetOutput = true;
_output = co;
}