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pythonscopepybrain

Trouble with the scope of variables in a class?

So I'm in the process of making a class in Python that creates a network (with pybrain) using solely the numeric input it's given {just a little process to get my feet wet in Pybrain's API}.

My problem is, I'm rather unfamiliar with how scopes work in classes, and while I basically have the program set up properly, it keeps returning a keyerror.

All the variables needed to be acted upon are created in the init function; the method I'm working on for the class is trying to call upon one of the variables, declared in the init function using the vars()[] method in Python. (you can actually see a portion of the code's...rough draft here: Matching Binary operators in Tuples to Dictionary Items

Anyways, the method is:

    def constructnetwork(self):
    """constructs network using gathered data in __init__"""
       if self.recurrent:
            self.network = pybrain.RecurrentNetwork  
            #add modules/connections here
       elif self.forward:
            self.network = pybrain.FeedForwardNetwork
       else:
            self.network = pybrain.network

       print vars()[self.CONNECT+str(1)]
       print vars()[self.CONNECT+str(2)]
       print self.network

(pardon the bad spacing, it didn't copy and paste over well.) The part that's raising the KeyError is the "print vars()[self.CONNECT+str(1)], which should retreive the value of the variable "Connection1" (self.CONNECT = 'Connection'), but calls a keyerror.

How do I get the variables to transfer over? If you need more information to help just ask, I'm trying to keep the quesiton as short as possible.

Solution

  • vars() returns a reference to the dictionary of local variables. If you used vars() in your __init__ (as the code in the post you linked to suggests), then you just created a local variable in that method, which isn't accessible from anywhere outside that method.

    What is it that you think vars() does, and what are you trying to do? I have a hunch that what you want is getattr and setattr, or just a dictionary, and not vars.

    Edit: Based on your comment, it sounds like, indeed, you shouldn't use vars. You would be better off, in __init__, doing something like:

     self.connections = {}
 self.connections[1] = "This is connection 1"

    then in your method, do:

     self.connections[1]

    This is just a vague guess based on your code, though. I can't really tell what you are intending for this "connection". Do you want it to be some data associated with your object?