Eliminate class allocators and deallocators?
Don
nospam at nospam.com
Thu Oct 8 05:58:08 PDT 2009
Steven Schveighoffer wrote:
> On Thu, 08 Oct 2009 07:26:37 -0400, Denis Koroskin <2korden at gmail.com>
> wrote:
>
>> On Thu, 08 Oct 2009 14:48:19 +0400, Steven Schveighoffer
>> <schveiguy at yahoo.com> wrote:
>>
>>> On Wed, 07 Oct 2009 17:54:35 -0400, Denis Koroskin
>>> <2korden at gmail.com> wrote:
>>>
>>>> On Wed, 07 Oct 2009 23:00:06 +0400, Sean Kelly
>>>> <sean at invisibleduck.org> wrote:
>>>>
>>>>> auto x = cast(MyClass) malloc(MyClass.classinfo.init.length);
>>>>
>>>> I would expect a dynamic cast to occur at this line. Which will
>>>> either result in an access violation (since you are trying to cast a
>>>> garbage to an object) or result in a null being returned.
>>>
>>> malloc returns void *, so no dynamic cast.
>>>
>>> -Steve
>>
>> I know malloc returns void*. I didn't know you can hijack type system
>> that easily.
>>
>> But then, if no dynamic cast takes place why cast(Object)cast(void*)0
>> cannot be evaluated at compile time?
>
> Your message made me test it :)
>
> import std.stdio;
>
> void *foo()
> {
> return cast(void*)0;
> }
>
> void main()
> {
> auto o = cast(Object)foo();
> writefln("here!");
> o.opEquals(o);
> }
>
> outputs:
>
> here!
> Segmentation fault
>
> So, no dynamic cast (dynamic cast would have looked at the classinfo of
> null, segfaulting before the output).
>
> So I would say, the fact that compile time evaluation doesn't work is a
> bug maybe?
>
> -Steve
CTFE is not yet supported for classes.
More information about the Digitalmars-d
mailing list