[Zope] Simple Python question

[Chris Meyers]

On Wed, Jul 24, 2002 at 09:09:55AM -0400, Ed Leafe wrote:
> <alert type="newbie">
> 
> 	How do I test if a value exists in Python? I'd really like to avoid 
> using try/except if possible. I need to do something like:
> 
> if defined(x):
> 	print 'x is cool'
> else:
> 	print 'x does not exist'
> 
> </alert>

This kind of depends on what 'x' is. If it should be in the REQUEST then you can do something like 

if REQUEST.has_key(x):
  #do stuff
else:
  #do some other stuff

If x is just a python script variable then it kind of depends on how your script is set up. If it is being passed in as a parameter then you can do:
if x:
  #do stuff
else:
  #do other stuff

This will basically check to see if x is None or an empty string "" or 0. If you are actually defining x in your script then you can also use the above code, but only after you define x. If x hasn't been defined and you try:
if x:
  #do stuff
you will get an error. If you are not sure when x will be defined, then you may have to use a try/except block.

HTH,
Chris

> 
>       ___/
>      /
>     __/
>    /
>   ____/
>   Ed Leafe
>   http://leafe.com/
>   http://foxcentral.net
> 
> 
> _______________________________________________
> Zope maillist  -  Zope@zope.org
> http://lists.zope.org/mailman/listinfo/zope
> **   No cross posts or HTML encoding!  **
> (Related lists - 
>  http://lists.zope.org/mailman/listinfo/zope-announce
>  http://lists.zope.org/mailman/listinfo/zope-dev )

-- 
Chris Meyers
Huttleston Data Design
7941 Tree Lane Suite 200
Madison WI 53717