The Final(ize) Challenge

[Ary Borenszweig]

Jarrett Billingsley wrote:
> On Mon, May 18, 2009 at 12:12 PM, Andrei Alexandrescu
> <SeeWebsiteForEmail at erdani.org> wrote:
>> Ok, now with the advent (or rediscovery) of allMembers which I had no idea
>> existed, we're ready to start some serious butt-kick reflection facilities.
>>
>> For starters, I'd like to present you with the following challenge. Given
>> any class C, e.g.:
>>
>> class C
>> {
>>    void foo(int) { ... }
>>    int bar(string) { ... }
>> }
>>
>> define a template class Finalize(T) such that Finalize!(C) is the same as
>> the following hand-written class:
>>
>> final class FinalizeC : C
>> {
>>    final void foo(int a) { return super.foo(a); }
>>    final int bar(string a) { return super.bar(a); }
>> }
>>
>> Finalize is cool when you need some functionality from an exact class and
>> you don't want to pay indirect calls throughout. All calls through
>> Finalize!(C)'s methods will resolve to static calls.
> 
> There are two challenging aspects that I'm running into.
> 
> The first is a more general statement about trying to generate
> functions with D's metaprogramming.  It is a huge pain in the ass to
> actually create a function with a given name, because the only way
> that I know this can be done is with a string mixin.  As soon as we
> venture into that territory, we have to consider things like how to
> convert a parameter type tuple into a string, and whether or not the
> .stringof a type will be correctly qualified (I've run into problems
> with this before, where some code in a library is not able to mix in a
> string because it doesn't import the same modules that the calling
> code does, and then you just get undefined identifier errors).  For
> the love of all that is holy, can we PLEASE get something like
> __ident("blah")?  This would be so much easier and would probably
> drastically reduce my use of string mixins in general.

Better __traits(ident, "blah")?