Procedures

[Dave Angel]

Greg Reyna wrote:
> <div class="moz-text-flowed" style="font-family: -moz-fixed">Learning 
> Python (on a Mac), with the massive help of Mark Lutz's excellent 
> book, "Learning Python".
>
> What I want to do is this:
> I've got a Class Object that begins with a def.  It's designed to be 
> fed a string that looks like this:
>
> "scene 1, pnl 1, 3+8, pnl 2, 1+12, pnl 3, 12, pnl 4, 2+4,"
>
> I'm parsing the string by finding the commas, and pulling out the data 
> between them.
> No problem so far (I think...)  The trouble is, there is a place where 
> code is repeated:
>
> 1. Resetting the start & end position and finding the next comma in 
> the string.
>
> In my previous experience (with a non-OOP language), I could create a 
> 'procedure', which was a separate function.  With a call like: 
> var=CallProcedure(arg1,arg2) the flow control would go to the 
> procedure, run, then Return back to the main function.
>
> In Python, when I create a second def in the same file as the first it 
> receives a "undefined" error.  I can't figure out how to deal with 
> this.  How do I set it up to have my function #1 call my function #2, 
> and return?
>
> The only programming experience I've had where I pretty much knew what 
> I was doing was with ARexx on the Amiga, a language much like Python 
> without the OOP part.  ARexx had a single-step debugger as part of the 
> language installation.  I've always depended on a debugger to help me 
> understand what I'm doing (eg Script Debugger for Apple Script--not 
> that I understand Apple Script)  Python's debug system is largely 
> confusing to me, but of course I'll keep at it.  I would love to see a 
> step-by-step debugging tutorial designed for someone like me who 
> usually wants to single-step through an entire script.
>
> Thanks for any help,
> Greg Reyna
>
>
You should post an example.  Otherwise we can just make wild guesses.

So for a wild guess, perhaps your question is how an instance method 
calls another instance method.  But to put it briefly, a def inside a 
class definition does not create a name at global scope, but instead 
defines a method of that class.  Normally, you have to use an object of 
that class as a prefix to call such a function  (with the exception of 
__init__() for one example).

class  A(object):
    def  func1(self, parm1, parm2):
           do some work
           self.func2(arg1)
           do some more work
    def func2(self, parm1):
            do some common work

q = A()
q.func1("data1", "data2")

Here we use q.func1()  to call the func1 method on the q instance of the 
class.   We could also call q.func2() similarly.  But I think you may 
have been asking about func1 calling func2.  Notice the use of 
self.func2().  Self refers to the object of the method we're already in.