Unmanaged - a D framework on github

[Benjamin Thaut]

Am 17.03.2013 16:20, schrieb Jakob Ovrum:
> On Saturday, 16 March 2013 at 14:40:58 UTC, D-ratiseur wrote:
>> new is overriden in TUObject because the purpose of the library is to
>> bypass the garbage collector and  to bypass the GC you have to
>> override new and delete.(at least according to the manual:
>> articles,mem managment).
>
> The documentation on this is old and misleading.
>
> Overloading of new and delete is deprecated (the delete operator in its
> entirety is deprecated).
>
> Having them overloadable was not a very good idea. The current approach
> is to have "new" always mean GC memory, which is why there is no need
> for delete. This way, code that uses 'new' won't break horribly or leak
> depending on the type involved, important for generic code. Code that
> doesn't use the GC has to be designed for it; you can't just remove the
> GC under everyone's noses and expect things to work.
>
> For different kinds of memory, you should simply use a different
> allocator. For example, here's a rough approximation of a pair of
> functions using malloc/free for class allocation:
>
> T alloc(T)() if(is(T == class))
> {
>      enum size = __traits(classInstanceSize, T);
>      auto p = enforceEx!OutOfMemoryError(malloc(size));
>      return emplace!T(p[0 .. size]);
> }
>
> void dealloc(T)(ref T obj) if(is(T == class))
> {
>      free(cast(void*)obj);
>      obj = null;
> }
>
> It can easily be overloaded to support all types.
>
> In the future, Phobos will have a custom memory allocator library, which
> modules like std.container will use, though to which extent is not clear
> (for example, will it also use the custom allocator for exception
> objects?). Nevertheless it will probably be a good base for other
> libraries to easily support non-GC allocators.

You still can't replace evertything with custom alloc templates and have 
nice syntax. There are at least two cases where it does not work nicely:

1) Arrays (no new T [size] syntax)
2) Inner classes (a template can't automatically capture the outer class)

So I think overloading new and delete actually has its place. But the 
way it is currently implemented in D is useless in my eyes.

Kind Regards
Benjamin Thaut