Scopes and exceptions

[Carsten Geckeler]

On Fri, 15 Dec 2000, Hans Nowak wrote:

> Magnus Heino wrote:
> > 
> > Could someone please explain this to me:
> > 
> > [magnus at daysleeper magnus]$ cat e.py
> > 
> > a = 'test'
> > b = 'test'
> > 
> > print 'a      = %s' % id(a)
> > print 'b      = %s' % id(b)
> > 
> > def func():
> >         print "'test' = %s" % id('test')
> > 
> > func()
> > 
> > try:
> >         test, '%s' % (a,)
> > except NameError, e:
> >         print 'e      = %s' % id(e)
> >         print 'a      = %s' % id(a)
> >         print 'b      = %s' % id(b)
> >         print "'test' = %s" % id('test')
> > 
> > [magnus at daysleeper magnus]$ python e.py
> > a      = 136227368
> > b      = 136227368
> > 'test' = 136227368
> > e      = 135997204
> > a      = 136227368
> > b      = 136227368
> > 'test' = 136227368
> > [magnus at daysleeper magnus]$
> 
> I don't understand what is so special about this? Python stores a string
> 'test' in memory... a points to this string, then b, so id(a), id(b) and
> id('test') all yield the same result. This is also the case after the
> exception. Variable e has a different id, because it's a different
> variable; not a string, but an instance of exceptions.NameError. 

It _is_ a string, but it's not 'test' but
	"There is no variable named 'test'"
therefore the ids are different.

But the point of Magnus' mail was if
	id(a) == id('%s' % (a,))
and it is *not*.

Cheers, Carsten
-- 
Carsten Geckeler:  carsten dot geckeler at gmx dot de
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