Re: [Wesnoth-dev] Improving compile time - forward class declarations

[David White]

I think this is a good idea, something which good coding practice 
dictates should have been done in the first place, and something which 
we should do now.

The only real caveat that I should note is that a container may only 
hold a complete type. i.e.

class myclass;
std::vector<myclass> v;

is not valid, though many implementations will allow it.

David

Yann Dirson wrote:

> There are a number of header files which only use some classes in
> function/method prototypes, and do not have any real use of the full
> class definition and all stuff defined in the corresponding header
> file.  Doing this causes many headers to be indirectly included by cpp
> files, and then surely increases compilation time.
>
> Ex: many headers include display.hpp, just because the function
> prototypes declare passing a display object by pointer or reference.
>
> Final #includers may not have a use for these includes, since they may
> just pass a pointer or reference they got as a parameter down to other
> functions, without really using them.
>
> mapgen and cavegen are perfect examples, where even the implementation
> has no use for the display object.
>
> Would there any problem to replace these includes by simple forward
> class declarations in the relevant header files (eg. "class display;"
> in mapgen.hpp) ?
>
>