Wood Programming Club Python Demo

This is an example pipe flow calculation repository built as a demonstration to Wood's programming club.

Richard Bell's original inspiration source code can be found on GitHub.

We covered a number of concepts:

Python code running as a script. Issues being:
- Inter-related functionality from different files is hard
- Distribution is hard
- Re-use is hard
- Dependency management is hard
- Versioning is hard
We added an __init__.py file to show how we could turn a folder of scripts into a Python pacakge.
We added a setup.py file to show how to create an installable Python package that will eventually:
- Have author and other metadata
- Express its dependencies on other Python code
- Describe what new packages it provides
- Describe dependencies for additional functionality like tests or deployment
- Describe command-line entry points into the python code.
We had a brief look at pip, Python's standard tool for installing packages defined with setuptools/`setup.py.
We looked at how installing Python packages in a virtual environment with virtualenv (and I used virtualenvwrapper) on top.
- This avoids conflicting global dependencies
- Means we can check we have just what we need for each individual project
- Can use multiple verions of Python together on the same machine with ease.
I installed ipython to show you a slightly nicer tool for playing with Python at the commandline.
We version-controlled the demo code so that we could look at what changed at every step and revert our source tree to previous versions should we need to.
I highlighted some features of my prompt that I use to make my life easier:
- Full current working directory
- Current Python virtual environment
- Current git status
- Exit status of last command (success/failure)
You can get my prompt for
- bash
- zsh
- (Use zsh if you can, it's great!)
I wrote some simple functions in wood_demo/equations.py to encapsulate the maths we needed to do in our program. This made them easy to use later on as we tried to combine the functions into a bigger system.
I wrote an object-oriented domain model just to touch on classes, methods, attributes and properties very briefly.
Very very quickly, I wrapped the whole thing up as a CLI tool using the click library (others are available), and exposed it as an entrypoint to the Python code via setup.py.

Installation

Clone this git repository from github.
I recommend setting up your own Python 3 virtualenv with virtualenvwrapper to play around installing things in.
In the top level of the source code repository (where setup.py is) run:
```
pip install -e .
```
to install the package as a linked install (-e), which means that as you change your source code it will be reflected in the installed code straight away. (This is not recommended for production.)

You should have the flow entry point now available in your virtual env, and you should be able to run:

flow 1000 25 400 100 1 360

and get

Pipe pressure loss = 0.0 kPa
Velocity = 0.80 m s⁻¹
Reynolds number = 1.27e+04
Friction factor = 0.01212

out.

Use
```
flow --help
```
to get auto-generate help information.

ch3pjw/wood_demo

Wood Programming Club Python Demo

Installation