pure and custom new / delete

[Benjamin Thaut]

Am 26.06.2012 19:19, schrieb Steven Schveighoffer:
> On Tue, 26 Jun 2012 12:05:55 -0400, Benjamin Thaut
> <code at benjamin-thaut.de> wrote:
>
>> Am 26.06.2012 18:02, schrieb Timon Gehr:
>
>>> You can cast function pointers to pure, or mark extern(C) memory
>>> allocation functions as pure.
>>
>> extern(c) is not an options as there is a structure of various
>> different allocators that implement a common interface which all is
>> written in D.
>
> extern(C) does not mean implemented in C, it just means C linkage. You
> can use arrays, classes, etc. in extern(C) functions. UFCS makes this
> really easy too:
>
> myalloc.d:
>
> interface Allocator
> {
> void * _alloc(size_t size);
> }
>
> extern(C) void *alloc(Allocator a, size_t size) pure;
>
> allocimpl.d:
> import myalloc;
>
> extern(C) void *alloc(Allocator a) // pure
> {
> return a._alloc(size)
> }
>
> mallocer.d:
>
> public import myalloc;
> import std.c.stdlib;
>
> // sample allocator
> class Mallocer : Allocator
> {
> void *_alloc(size_t size) { return malloc(size);}
> }
>
> main.d:
>
> import mallocer;
>
> void foo(Allocator a) pure
> {
> a.alloc(200);
> //a._alloc(200); // fails as expected
> }
>
> void main()
> {
> foo(new Mallocer);
> }
>
> -Steve

Thanks this works, but it seems to be a very ugly hack just to work 
around the type system. Also I have templated allocator functions I can 
not use this trick on. This is going to be a lot of work to get done 
properly, so I just ignore pure for now I think.