Partial classes

[Regan Heath]

On Mon, 25 Jun 2012 16:26:27 +0100, Manu <turkeyman at gmail.com> wrote:

> I suspect this isn't possible in a compiled language like D, but I wonder
> anyway, has anyone considered partial classes in D? Are they technically
> possible?
> How would they work? Would it depend on link-time code generation?
> I can imagine an implementation where each 'part' occupies a separate
> allocation, and some pointer in Object or somewhere like that (somewhere
> near the typeinfo pointer) binds them together.
>
> I often find myself wanting to add some extra pizazz to classes using
> template/mixin magic, but I may not have control over the original code
> where it is defined...
> C# at least can do this, and it's very useful in many situations...

I thought that the various parts of partial classes in C# had to be  
compiled together.  For example, I once tried to put a partial class into  
a C# dll, and the rest in a C# executable using that first dll and it just  
plain wont let you do this.

However, the c# code generated for me by sqlmetal produces a partial class  
derived from a DataContext (in one file), which I can extend and/or modify  
by implementing the rest of the partial class (in another file), in the  
same project (exe or dll) and if I compile them together I actually just  
get one merged class.

D could easily implement a partial class feature with the restriction that  
they need to be compiled together.  But IMO unless this is a trivial  
feature to implement, I wouldn't think it would be high on the priority  
list just yet.

Partial classes make customizing auto generated (especially repeatedly  
auto generated) code much easier.  #c uses them in it's form designer,  
placing all the designed code in a partial class in one file, and all user  
code in another file (in the same partial class).

R


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