Easy questions from a python beginner

[John Posner]

On 7/14/2010 12:06 PM, Ethan Furman wrote:

> ... Have you tried this?
>
> --> def foo():
> ... print locals()
> ... blah = 'interesting'
> ... print locals()
> ...
> --> foo()
> {}
> {'blah': 'interesting'}
>
> As can be clearly seen, blah does not exist before the assignment -- the
> *name* blah has not been *bound* to an object yet, which is also what
> the error message says when you try to use it before it exists:

As already cited, according to Section 4.1 "Naming and binding" in the 
Language Reference, the name "blah" *does* exist before the assignment. 
That's the implication of this phrase:

   If the name refers to a local variable that has not been bound,

(BTW, "has not been bound" should really be "is not currently bound", to 
allow for use of *del* earlier in the block.)

Try this:

#--------------
def foo():
     print "1. varnames:", globals()['foo'].__code__.co_varnames
     print "2. locals:", locals()
     blah = 'interesting'
     print "3. locals:", locals()

foo()
#--------------

The output (Python 2.6.5) is:

1. varnames: ('blah',)
2. locals: {}
3. locals: {'blah': 'interesting'}

-John