On 10/5/10 9:15 CDT, Steven Schveighoffer wrote:
On Tue, 05 Oct 2010 10:06:58 -0400, Mafi <[email protected]> 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
If you only want to intercept a few specific calls, you may want to use
alias this and simply define the appropriate methods. They will be found
by name lookup before alias this kicks in.
For intercepting all calls even to method names you don't know, indeed
opDispatch is the way to go.
Andrei
