[Tutor] Test if name is defined?

[Terry Carroll]

On Mon, 10 Feb 2003, Sean 'Shaleh' Perry wrote:

> On Monday 10 February 2003 21:26, Terry Carroll wrote:
> > Is there a way to test to see if a variable is defined other than with the
> > exception system?
> >
> 
> In a recent enough python:
> 
> def defined(thing):
>     return (thing in locals()) or (thing in globals())> 
> 
> or, old way:
> 
> def defined(thing):
>     return (locals().has_key(thing)) or (globals().has_key(thing))

Thanks; but that didn't work.

I tried:
========
def defined(thing):
    return (locals().has_key(thing)) or (globals().has_key(thing))

x = 1

if defined(x):
    print "x is", x
    
if defined(y):
    print "y is", y
========

and got:

========
Traceback (most recent call last):
  File "tryit.py", line 10, in ?
    if defined(y):
NameError: name 'y' is not defined
========

Same error with both versions.

-- 
Terry Carroll        |  "To have this rare opportunity
Santa Clara, CA      |    is a rare opportunity."
carroll@tjc.com      |    - Houston Rockets' Yao Ming, on being named
Modell delendus est  |    starting center for the 2003 NBA All-Star Game