[Tutor] defined()

[Bob Gailer]

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
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