[C++-sig] Re: return_self_policy

[Nikolay Mladenov]

David Abrahams wrote:
> 
> Nikolay Mladenov ?nickm at sitius.com? writes:
> 
> ? Posting return_self policy implementation
> ?
> ? Nikolay'''
> 
> Nikolay,
> 
> This is wonderful!  Now, I hate to do this, but I just realized that
> this should really be generalized to something which takes an
> argument number as its parameter and returns that argument:

I have already thought about it (I expected it from you ;-) )
and it is already there in some form:
the definition of return_self_policy is

	template<class Base>
		struct return_self_policy : 
			detail::return_arg<0, Base> {}


> 
>  return_identity?0?                     // error
>  return_identity??, return_identity?1?  // same as return_self_policy
>  return_identity?2?                     // return the 2nd argument
>  return_identity?3?                     // return the 3rd argument
>  ...
> 
> etc.

So return_arg is as your return_identity, although return_arg<0> is not
an error but return_self.


> 
> Don't you think that makes more sense?  Would you mind making this
> modification?

I agree that it makes more sense, but I am not sure how much the "more"
is.

Generally I don't mind.

> 
> Thoughts, objections, screaming...?

My question is: why start counting from 1? This will make the code more
complicated and difficult to read.

> 
> --
> Dave Abrahams
> Boost Consulting
> www.boost-consulting.com


Regards,

Nikolay