[Tutor] confusion about imports

[Chris Hare]

Good advice - thanks for that.  And I think you're right - I think what is happening is in fact a bunch of circular references.  As I resolve issues, I will be looking for those!  Appreciate all the advice!

On Jul 9, 2012, at 5:16 PM, Dave Angel wrote:

> On 07/09/2012 11:56 AM, Chris Hare wrote:
>> So, I have to admit, imports have me really confused.  I am trying to break apart a 10,000+ line single file into various files, one for each class, and one containing a whole bunch of functions which are used by a lot of classes.  Some of those functions use calls to methods in a Class.  Even though the Class has been imported, I get a nameError where trying to use the class.  I have read about Classes and packages and modules, but import just has me confused.
> Something I haven't seen explicitly mentioned in this thread is that
> when you make those modules to hold classes DO NOT make the module name
> the same as the class name.
> 
> If you have a class MyClass defined in your 10k file, and you want to
> move it to a separate file, and if you really wanted to dedicate the
> file to a single class, then the file might be called myclass.py and the
> references to it would like something like:
> 
> import myclass
> ...
> obj = myclass.MyClass(arg1, arg2)
> 
> or alternatively,
> 
> from myclass import MyClass
> ...
> obj = MyClass(arg1, arg2)
> 
> You wouldn't believe how much confusion people get into when they have
> module names that look like class names.
> 
> 
> Another thing is that you probably want several related classes and
> functions in each module.  This is not Java.  At that point, you might want
> 
> from  people  import MyFirstPeopleClass, MySecondPeopleClass, peoplefunction
> 
> 
> Finally, upon more careful reading of your original query, you may have
> circular dependencies happening here.  A function may use class methods,
> and class methods may use the function.  But if both are true, then put
> them in the same module.  Having one module import a second one which
> imports the first is an invitation to disaster.  And a special place in
> debugging hell is reserved for those that try to import the script that
> invokes it all.
> 
> -- 
> 
> DaveA
>