learning-python question

[David Goodger]

on 2000-07-28 23:02, gbp (gpepice1 at nycap.rr.com) wrote:
> I'm new to python but it looks like your varible is out of scope.  Try
> declaring it as a global (just put the work global in front of it) or
> try moving it so its inside the function.  It you declare a varible at
> top level its isn't automatically global.  Its local to the top level.
> 
> JeremyLynch at fsmail.net wrote:
>> count = 5
>> 
>> def count_func()
>>   print count
>>   count = count + 1
>> 
>> count_func()
>> 
>> Why can count_func() not see count (it throws up a 'name'
>> or 'attribute' error)

Almost. The variable "count" is global, which means it's visible inside
count_func(). But when you say "count = count + 1", you're first referring
to the global variable count, adding 1 to its value, then assigning that
value to a new local variable count. This is not allowed in Python; you
cannot refer to an unqualified name both globally and locally in the same
function.

The solution is to put "global count" inside the function, *before* you
first refer to the variable (the first line is a good place).

Why not make count_func into a real function? (I assume that your real
intention is more complex than the example above.) Viz:

  def count_func(count):
    print count
    return count + 1

  count = 5
  count = count_func(count)

-- 
David Goodger    dgoodger at bigfoot.com    Open-source projects:
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