Fun with allMembers

[Lutger]

Andrei Alexandrescu wrote:

> Shin Fujishiro wrote:
>> Hi,
>> 
>> I've had fun with the allMembers traits over the past few days and found
>> it more powerful than I thought.
>> 
>> __traits(allMembers, T) returns the member names of T. As some might
>> already know, T is not restricted to a class or struct; it can also be
>> an enum, template, or even module. Try this:
>> --------------------
>> enum E { a, b, c }
>> template T() { int x, y, z; }
>> import std.stdio;
>> pragma(msg, __traits(allMembers, E).stringof);
>> pragma(msg, __traits(allMembers, T).stringof);
>> pragma(msg, __traits(allMembers, std.stdio).stringof);
>> --------------------
>> You'll like the result :). It must be usable!
>> 
>> For example, using allMembers with enums, I could implement
>> enumToString and enumFromString without defineEnum.
>> Code: http://codepad.org/HVvPjoI7
>> 
>> So, what other uses could there be?
> 
> Wow, I didn't know about this! It might as well be everything needed for 
> a full-blown compile-time reflection package!
> 
> To answer your question: for starters, try to implement BlackHole and 
> WhiteHole as explained here:
> 
> http://erdani.dreamhosters.com/cranking-policies-up.pdf
> 
> 
> Andrei

See also this article from the author of PyD: http://kirkmcdonald.blogspot.com/2007/07/inadequacies-of-traits.html
(Not that it isn't very powerful as is.)