existence of a variable

[Stefan Schwarzer]

Hello Martin,

martindvorak at my-deja.com schrieb:
> What is the best way to determine existence
> of a variable in Python (I need to check
> if a variable is defined and if so,
> delete it)?

If you know in which module (class etc.) the variable would be,
you may use the builtin hasattr function:

[warpy|d:/]echo a = 7 >test.py
[warpy|d:/]python
Python 1.5.2 (#0, Jun 27 1999, 11:23:01) [VisualAge C/C++] on os2
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> import test
>>> hasattr( test, 'a' ), hasattr( test, 'b' )
(1, 0)
>>> class testclass:
...     def f(): pass
...
>>> hasattr( testclass, 'f' ), hasattr( testclass, 'g' )
(1, 0)

<Disliking-the-inconsistency-of-hasattr-vs.-has_key>-ly y'rs
Stefan