Spreading a class over multiple files

[Terry Reedy]

On 6/5/2016 2:55 AM, Mark Summerfield wrote:
> Sometimes I want to spread a class over multiple files.

My experience with trying to work with two do-all classes in idlelib has 
engendered a dislike for such.  It is hard to find things in a 
kitchen-sink class.  To switch IDLE from being a multi-window 
application to having multiple panes in a single window, both must be 
refactored.

> My primary use case is when I create a "Model" class to reflect an
> entire SQL database. I want a model instance to provide a single
> point of access to the database, but the database has many tables
> each requiring its own methods since they differ in their structure,
> purpose, validation needs, etc.

I would consider a master database ('Model') class, a base table class, 
and a subclass class for each table or group of similar tables.

> A secondary use case is when I create "MainWindow" classes in GUI
> programming and have lots of methods to reflect all the actions
> (e.g., menu options and toolbar actions, plus interaction with the
> main widget(s)).

With tk and tkinter, at least, implementation functions do not have to 
be in the same file as the menu or toolbar definitions.

-- 
Terry Jan Reedy