Implemented 'Mandatory flags' per issue #44

[kppullin]

Implemented 'Mandatory flags' based on the thread:
#44.

Similar to the fix from this pull request:
#70, but is additive
and does not break the existing semantics of 'required' arguments.

If this pull request is accepted I'll also update the docs : )

[tj]

personally i prefer to leave this portion to the program logic, since it could be more complex, such as if --foo is used then --bar is required as well etc

[millermedeiros]

@visionmedia maybe a solution for the future is to allow objects on the .option() calls, like:

program
  .option({
    flags : '-f, --foo <file>',
    description : 'Foo option rocks',
    required : true,
    // specify that this option depends on other ones
    depends : '--bar, --ipsum',
    validate : function(value, program){
      // check if supplied argument is valid
      return value.indexOf('.') !== -1;
    }
  });

this would increase the flexibility and group all the logic related to arguments parsing/validation.

[tj]

meh I think that's getting too complex, it's easy to defer most of that to program logic

[thesmart]

Dude, seriously. I expected this feature to be part of commander. Wondering what is the point of commander if not to require arguments?

[tj]

don't use it if you dont want to? options are one thing but arguments can be parsed in a nearly infinite number of ways, I'd rather not handle that at all, frankly I want to get rid of sub-command support (as it is now) as well, and go with git-style sub commands

[tj]

leaving this up to the user, it's not hard to add a few conditionals

[EvanCarroll]

I don't agree with this position you've taken @visionmedia . It's one of those cases where 99% of the users want the barest most minimal functionality. It's a very ideological stance to take that because things can get more complex no accommodations should be made.

That said, I agree with your conclusion -- those that can't live with your decision should go elsewhere. Perhaps though you could make that more apparent in the docs. This is one of three bug reports that references this functionality. I imagine if there was an FAQ it'd be the foremost asked question. Would you accepted a doc-patch that said this feature would not be implemented, with a reference to optimist which seems to be all around more complete (a larger library)?

[tj]

it's trivial to do if (!foo) throw new Error('<foo> required'). If we added support for this then people would want a way to customize the output etc, which then becomes more obscure, gaining pretty much nothing. Almost always there's some form of logic applied to arguments anyway, validation, conditions based on the env etc...