[Python-Dev] type categories -- an example

[Andrew Koenig]

Casey> In general you wouldn't care whether is was a sre_foo or an sre_bar, just if 
Casey> it acts like a compiled regular expression, and therefore supports that 
Casey> interface. So, the real solution would be to have re assert that interface on 
Casey> whatever the compiler returns so that you can check for it, something like: 

Casey> if ISre.isImplementedBy(unknown_ob):
Casey>   # It's a regex

Casey> Where ISre is the compiled regular expression interface object. If the 
Casey> implementation varies the test would still work. Even if the interface 
Casey> varied, the test would work (but it might break other stuff).

Exactly.