Using an object inside a class
Gary Herron
gherron at digipen.edu
Mon Jan 23 15:23:25 EST 2012
On 01/23/2012 11:44 AM, Jonno wrote:
> I have a pretty complicated bit of code that I'm trying to convert to
> more clean OOP.
>
> Without getting too heavy into the details I have an object which I am
> trying to make available inside another class. The reference to the
> object is rather long and convoluted but what I find is that within my
> class definition this works:
>
> class Class1:
> def __init__(self):
>
> def method1(self):
> foo.bar.object
>
> But this tells me "global name foo is not defined":
>
> class Class1:
> def __init__(self):
> foo.bar.object
>
> Obviously I want the object to be available throughout the class (I
> left out the self.object = etc for simplicity).
>
> Any ideas why I can reference foo inside the method but not in __init__?
>
>
You're not telling us everything. In fact, with the code you gave us,
neither method1 nor __init__ will work correctly, because you have not
defined foo *anywhere*.
Without knowledge of what you are *really* doing, I'll say this: Both
method1 and __init__ are methods of Class1, and both have the same rules
for looking up variables. If either method binds a value to foo, then
your code may access it:
class Class1:
def __init__(self):
foo = whatever # Local to this method
foo.bar.object
If the method does not bind it, then Python will look in the class for
foo. This could work
class Class1:
foo = whatever # Available to all instances
def __init__(self):
foo.bar.object
If that fails, Python will look in the globals, so this could work:
foo = whatever # Available across the full module
class Class1:
def __init__(self):
foo.bar.object
Python goes on one further level when searching for a variable -- that
being the builtins.
--
Gary Herron, PhD.
Department of Computer Science
DigiPen Institute of Technology
(425) 895-4418
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