[Boost-users] program_options: main and other translation units

Subject: [Boost-users] program_options: main and other translation units
From: Hicham Mouline (hicham_at_[hidden])
Date: 2009-12-10 09:35:56

Hello,

I have a main.cpp translation unit with the main(int argc, char* argv[])
function.
My application runs in 1 of 4 modes. The mode is selected by the command
line options, something like

--mode1
--mode2
--mode3
--mode4

In main(), I have defined a mode_options instance of options_description,
added these modes to it and defined the variables_map 'vm' that will be
passed around to functions (1 for each mode) that reside in other
translation units.

I then get to a try/catch block, where:

I store( command_line_parser(argc, argv).options(mode_options).run(), vm );
notify(vm);

I have a sanity check that only 1 and at least 1 of the 4 modes is selected.

I then call the function relevant to the mode selected, and pass to it 'vm'.

In each of these other functions, I have other instances of
options_description, reuse the same 'vm' and store again in vm the parsing
ran on the appropriate options_description instance.
Each mode option has specific suboptions.

Question 1: 
I want the help option to print usage for all modes and all suboptions if no
mode is selected.
I want the help option to print usage for just 1 mode if a mode is selected.

Question 2:
I still want to program_options to throw if an unrecognized option is input,
however, I throw my own exceptions if an option for mode_i is set with
--mode_j for e.g.

Question 3:
I may eventually move to a GUI (probably c#-based) for passing options.
Is there any particular advice to isolate the machinery of program_options
from the functional part of my application.

A big thanks to the library developer(s) and to the mailing list
contributors for all the useful answers.
Best regards,

H