rationale for function and delegate

[Jonathan M Davis]

On Saturday 16 October 2010 01:40:55 Paulo Pinto wrote:
> Hi,
> 
> while reading TDPL I start wondering what is the background between
> function and delegate.
> 
> They seem to provide more or less the same funcionality, except delegate
> allows the capture
> of the function declaration environment.
> 
> Most of the programming languages with support for closures only have one
> way of doing it.
> 
> Why is D providing two ways of doing it? For me sounds like a feature
> similar to register, or
> inline for doing what should be the compilers work. Deciding the best
> implementation for the
> closure.
> 
> Thanks,
> Paulo

I believe that the two main reasons are

1. function pointers have less overhead.

2. If you want to use function pointers when calling C functions, you need 
function pointers rather than delegates.

but there are probably others.

- Jonathan M Davis