checking whether a var is empty or not
Dave Cole
djc at object-craft.com.au
Wed Aug 4 02:29:29 EDT 2004
Dave Benjamin wrote:
> In article <opsbxubr1g1v4ijd at musicbox>, Pierre-Frédéric Caillaud wrote:
>
>> This smells like PHP to me...
>>
>>if var is not None:
>> if var has not been assigned, it raises an exception.
>> if var has been assigned, it contains a value which can be None or
>>someting else.
>>
>> This is different from PHP where you can't know if a variable exists or
>>not, because a non-existent variable will contain null if you check it,
>>and putting null in a variable is like deleting it, but noone knows
>>because there's no way of checking if a variable really exists, etc.
>
>
> No, in PHP, you can find out if a variable exists using isset(). And trying
> to dereference an uninitialized variable will generate a warning if you have
> error reporting turned up all the way (error_reporting(E_ALL)).
>>> def isset(var):
... return var in globals()
...
>>> print isset('var')
0
>>> var = 43
>>> print isset('var')
1
Not that I can see any good use for this :-).
- Dave
--
http://www.object-craft.com.au
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