Re: pure and custom new / delete

[Steven Schveighoffer]

On Tue, 26 Jun 2012 12:05:55 -0400, Benjamin Thaut  
<c...@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