[Tutor] defined()

Bob Gailer bgailer at alum.rpi.edu
Tue Apr 4 03:10:34 CEST 2006

Hugo González Monteverde wrote:
> Alan Gauld wrote:
>> Which language(s) do you know that has such a feature?
>> And why do you consider it so useful that you expect to find
>> it in Python?
> I'm not the original poster, but being a perlhead before, I can say it 
> exists in Perl. It is very often used too.
And you can "roll your own" in Python:

def defined(name):
    return name in globals()
> I used to miss it at first, but normally I now do the right thing 
> semantically. Counting on the variable being defined or not is simply 
> another bit of information. Assigning a value for that case is much cleaner.
> It is not used for black magic in Perl, AFAIK. Just normal testing.
> Hugo
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor

More information about the Tutor mailing list