On 8/30/10 20:04 PDT, dsimcha wrote:
I've been toying for a long time with the idea of a std.mixins for Phobos that would contain meta-implementations of commonly needed boilerplate code for mixing into classes and and structs. I've started to prototype it (http://dsource.org/projects/scrapple/browser/trunk/std_mixins/std_mixins.d). So far I have a mixin for struct comparisons, which is useful if you need a total ordering for use with sorting or binary trees, but don't care exactly how that ordering is defined. I've also got a mixin that converts a class to a Singleton, and uses thread-safe but efficient mechanisms to deal with the __gshared singleton case.
Upon a second look I think the Singleton implementation is not up to snuff and reflects a common misunderstanding of the pattern.
The point of the Singleton is that you can instantiate it with a derived class. Otherwise, it's the less interesting Monostate pattern. The code as is right now uses hardcoded calls to new, and it shouldn't.
Andrei
