Avoid identity collisions for simmilar method names

[augustohp]

Our generated identity for cache ids considers method name + method arguments which has a possibility for collision.

If we consider the class name owning the method being called as well, we solve this issue.

[filhodanuvem]

I wrote a draft about this issue here, but I prefer that identity generator method
receive the entire instance caller instead of his namespace, this would be more generic.

Problem: every identity generator method should to test if instance is really an object ?

Benefit: I could write a new IdentityGenerator using the hash object, for example.

What do you guys think?