Confused about nested scoping

[Bjorn Pettersen]

They're nested lexical scopes, not dynamic scopes (which is what you were
expecting).

An example of a nested lexical scope would be e.g.:

1  def outer():
2      spam = 'bacon'
3      def printspam():
4          print spam
5      printspam()

1: Defines an outer function
2: creates a variable, spam, that is local to outer
3: creates a lexically nested function, printspam
4: If you do from __future__ import nested_scopes,
   this line prints the contents of the variable spam
   set in the lexically enclosing scope on line 2.
   In traditional Python this would raise a NameError
   since spam isn't in the local or the global 
   namespace.

hth,
-- bjorn
   

-----Original Message-----
From: Stephen R. Figgins [mailto:fig at monitor.net]
Sent: Wednesday, April 18, 2001 5:18 PM
To: python-list at python.org
Subject: Confused about nested scoping


I seem to be misunderstanding what nested scopes do. 

>From AMK's summary of 2.1 changes: 

  Put simply, when a given variable name is not assigned a value
  within a function (by an assignment, or the def, class, or import
  statements), references to the variable will be looked up in the
  local namespace of the enclosing scope. 

Here is what I tried: 

from __future__ import nested_scopes

def printspam():
	print "spam has value %s" % (spam)

def scopetest():
        spam = 'bacon'
	printspam()

spam = 'eggs'
printspam()
scopetest()


I figured without nested scopes I would get 

  spam has value eggs
  spam has value eggs

But I thought with nested scopes I would get 

  spam has value eggs
  spam has value bacon

Because the second printspam's enclosing scope would be that of
scopetest in which I had reassigned spam.

But I still get eggs with my spam.

What am I misunderstanding?

-Stephen
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