Type wrapping blockers

[Steven Schveighoffer]

On Tue, 05 Oct 2010 10:06:58 -0400, Mafi <mafi at example.org> wrote:

> Am 05.10.2010 14:50, schrieb Steven Schveighoffer:
>> One of the good goals of D I think is to be able to automatically
>> encapsulate a type, and all its attributes/functions, in order to
>> slightly alter the functionality. I think this is probably a pattern,
>> but I don't know what it is (Interceptor?).
>>
>> One of the best methods to wrap a type is to use opDispatch. But there
>> are some problems that block this. It might be good to get a bug report
>> that gathers these together. I have one that I just ran into -- IFTI and
>> literals. Basically, if you have a function:
>>
>> void foo(short x);
>>
>> you can call foo(1) no problem.
>>
>> But if you *wrap* the type that contains foo, you cannot use opDispatch
>> to implement foo(1), because IFTI treats 1 as an int. So what you get is
>> an instantiation of opDispatch like this:
>>
>> opDispatch!("foo", int)(1) Which then cannot call foo, because you
>> cannot cast int to short.
>>
>> Does anyone have any other blockers that prevent type wrapping? Does
>> anyone have any ideas on how to fix the above issue?
>>
>> -Steve
> Iff you are only wrapping one other thing (ie struct, class...), you  
> should be able to use alias this. It should in my opinion correctly  
> resolve to foo(short). If dmd doesn't find foo in your wrapper it should  
> look for foo in the alias before saying that 1 has to be int.
> But I didn't test.

Alias this does not allow interception of calls.

I want to do something inside opDispatch besides just calling foo(1).

-Steve