On Wed, Apr 29, 2009 at 2:52 AM, Georg Wrede <georg.wr...@iki.fi> wrote: > Jarrett Billingsley wrote: > >> Don't you love it? "Most C++ template features are discovered." So are >> D's. > > Well, one could say that this is the very definition of a well working > metaprogramming system. After all, the whole idea of templates is to let the > programmer invent new ways to use the lanaguage, the compiler, and the > template system.
That's not.. really at all what the issue is here. The issue is more that most of the metaprogramming features in D are completely unspecified, and when we discover that something works, it's hard to tell if it's _supposed_ to be that way or if we're taking advantage of some weird bug in the compiler. Show me a page that documents .stringof! Thought not. As some other examples, did you know it's possible to get the names of the fields of a struct type (and probably a class type too with a similar method)? It only works under extremely contrived circumstances, using .stringof, and parsing out the names yourself from a very horrible-looking string. It's also possible to get the name of a local variable by instantiating a template in a local scope and parsing a horrid .mangleof string. You can also determine some (not *all*, but some) interesting properties of functions and methods - things like final, static, abstract - by creating dummy inherited classes and attempting to do awful things to them. Metaprogramming should be _well-specified_ and _orthogonal_. I agree with you that the _possibilities_ of metaprogramming should be almost boundless and should allow you to come up with your own DSLs. But the compiler shouldn't hold information about your program "ransom" and make you work so goddamn hard to get at it. I should be able to just write, I don't know, __traits(parameterNames, f) and get a tuple of parameter names! I'm tired of puzzling out information that should be directly available!
