checking one's type

["Martin v. Löwis"]

belinda thom schrieb:
> I've been using the following hack to determine if a type is acceptable
> and I suspect there is a better way to do it:
> 
> e.g.
> 
> if type(s) == type("") :
>    print "okay, i'm happy you're a string"
> 
> If anyone knows a better way, I'm all ears.

There are several way to improve it. In order from smaller to larger
changes:
- don't use type(""), instead, use str:
  if type(s) == str:
  [notice: this works only from Python 2.2 or so]
- you can compare types by identity and don't need to compare for
  equality:
  if type(s) is str
- you can do instance tests with isinstance:
  if isinstance(s, str):
- try avoiding instance tests altogether. Instead, just let callers
  pass anything, and then let the operations fail if they can't handle
  the types.

Regards,
Martin