[boost] Re: [name_params] Flag arguments?

From: Daniel Wallin (dalwan01_at_[hidden])
Date: 2004-11-20 11:51:48

Rene Rivera wrote:
> Dave, Daniel,
> 
> I have a use case which would be nice to support. I have some functions 
> which take some number of flag arguments, akin to:
> 
> void foo(const char * name, float value, bool flag1 = false, bool flag2 
> = false)
> {
>     std::cout << name << " = " << value << "\n";
> }
> 
> And I can add the named arg interface, so I can use it as:
> 
>     foo((value = 5.2f, name = "baz", flag1 = true));
> 
> But ideally I'd like the use to look like:
> 
>     foo((value = 5.2f, name = "baz", flag1));
> 
> That is, the presence of the keyword is enough to set the argument to 
> true. Possible?

Not with the current library, but it could very easily be added. Perhaps
something like:

   bool flag1_ = args[flag1.implicit(true) | false];

What do you think? Dave? We could also just have all keywords have an
implicit value true, but I think that might cause some problems for
users.

-- 
Daniel Wallin