My Python Coding Conventions

Coding Conventions Etc.

In reading my code it may be of some use to know what conventions I have ( tried ) to follow. The code has been developed over quite a period of time so the standards are not uniform. What I write here are the standards that are in quite a bit of the code and the directions that I am trying to move. In all of the coding consistency is an important standard, I have a ways to go. I am now only coding in Python 3.6 or up. Here are some types of conventions. Ultimately if you want to understand the code, read it. I work hard to make it readable, so please try, you can let me know of shortcoming, but note that I am aware of the fact that it still need improvement.

Names

I try to be consistent: this is good but have not been very successful in standards: I keep changing my mind. I am avoiding short names and try to make names descriptive enough that they are somewhat self documenting. References are often copied across objects for easy access ( lots of parameters for example ); when this happens the name of the object is generally ( should be always ) the same in both objects.

Formatting

Nothing special here but I like white space and use a lot. This is not standard Python. But this is what I like.

Docstrings

I am working towards using them but have not arrived at a format that I both like to read and which is quick enough to write. Not good as of 2017 Jan

Imports

• In most cases use the format "import xyz" so the name space is not polluted and so it is easy to identify just what an imported class is.
• In in objects that are almost all GUI then using "from Tkinter import *" is ok but better is: "import Tkinter as Tk"
• I normally have only one or a few classes in a file so there are a lot of files and a lot of what I call "local imports".
• Almost all imports are at the top of a file, std library imports first then "local imports".

Object Orientation

Almost everything is a class. Not much in the way of module functions, not many classes in a module. I think my Java experience has led me to overuse classes and under use functions.... at the module level.

Documentation for Class Instance Methods

Look something like this:

   def create_class_from_strings( self, module_name, class_name):
       """
       This will load a class from string names
       It makes it easier to specify classes in the parameter file.
       I believe it is used for both the comm drive and the "processor"
       args:  strings
       ret:   instance of the class
       Side effects Class created 
       """

The comment should give the intent of the method, some hint as to the args ( which hopefully have good names ), and some info. on the return value. zip means nothing, void....

I am moving toward using __ and _ as prefixes for more private methods, but have not gone too far in this direction.

Application Structure

coming...

MVC Structure

I try to separate the Model, View, and Controller into separate modules and classes. The View is the class GUI.

GUI Structure

coming...

• Construct frame by frame in a subroutine returning the frame reference, the caller then places the frame. Typically constructed and placed from top to bottom from left to right.
• Elements:
  • Buttons for application management: restart the app, edit the parameters, edit the log, help.
  • Buttons.... for the application.
  • A text control for application messages, sort of a mini console for the application.

Application Parameters

see: Configuration Files For Python

Typical Application Functionality

coming...

MultiThreading

In any GUI code using Tkinter if the GUI kicks off a long running piece of code the GUI becomes unresponsive while the code runs. To avoid this you can use a second thread. This is frequently what I do. I call the two threads the gui thread, and the helper thread. To coordinate the two I have two queues, one from gui thread --> helper thread and from helper thread --> gui thread. I try to isolate the code for each thread into its own modules and classes, and comment the code as to the required thread in cases where I think there might be doubt.

Python Logging

I usually implement the standard python logging utility, messages into a file configured by parameters.py, the gui typically has a button to view this file.

Links

• Configuration Files For Python
• Configuration Files For Python