std.patterns: it was about time

[Andrei Alexandrescu]

In wake of the increasing power of templates in D2, I am starting the 
std.patterns module, which is to contain boilerplate for a number of 
common design patterns (as in the GoF book). For now I'm adding a 
Visitor implementation, which was lying in my codebase for a while.

http://ssli.ee.washington.edu/~aalexand/d/web/phobos/std_patterns.html
http://ssli.ee.washington.edu/~aalexand/d/web/phobos/std_patterns.d
Comments and suggestions are as always welcome.


Andrei