Re: [boost] [program options] why is ->multitoken() not default for vector arguments?

Subject: Re: [boost] [program options] why is ->multitoken() not default for vector arguments?
From: Vladimir Prus (vladimir_at_[hidden])
Date: 2009-06-08 14:52:43

Thorsten Ottosen wrote:

> Hi,
> 
> I have code like
> 
>          bpo::options_description desc("Allowed options");
>          desc.add_options()
>          ("help", "produce help message")
>          ("file", bpo::value<std::string>(), ".sug file with graph
> description")
>          ("new_edge", bpo::value<std::vector<unsigned>>()->multitoken(),
>           "two numbers denoting the new edge");
> 
> I had to add the ->multitoken to make a command like
> 
> ./clique_tester.exe --new_edge 1 2 --file bug1.sug
> 
>                               ^^^^^^^^
> work.
> 
> This seems wierd. Why would I want a vector of values, yet only parse
> one of the trailing argument?

multitoken options are evil, because of parsing ambiguities. The motivating
examples for vector<string> option is the -I option of a compiler -- where
each instance of -I takes a single path -- and which seem to work just fine.

- Volodya