# Notes for developers¶

Note

There is a makefile with handy targets for running tests, etc - use make list to show these.

## Setup¶

One should install PythiaPlotter in “editable” mode using pip. This is easily done using make installe (note the e), or make reinstalle to uninstall and reinstall.

Developers should install the packages in tests/requirements.txt for running the tests, and docs/requirements.txt for making the docs:

pip install docs/requirements.txt
pip install tests/requirements.txt


## Design Notes¶

The program is designed to be easy to extend in the event that more support needs to be added for different input or output formats. Because of this, there is a strong divide between the parsing part of the program, and the plotting/printing part.

These two parts communicate by exchanging an Event object, which contains a NetworkX MultiDiGraph object that holds the graph structure and particles.

In addition, there is a divide between the physical objects in an event, and the structure that connects them. This offers several advantages:

• uniform way to access particle relationships regardless of input or output mode
• separation of physical particle attributes from graph structure and attributes (e.g. parent nodes, etc)
• separation of visual attributes from physical attributes.

The last point is important: this way, we can easily assign a NodeAttr object to each node, and an EdgeAttr to each edge, to hold the display options and decouple the visual attributes from the physical attributes. By sub-classing those *Attr objects for different output formats, we can easily implement a new output format without interference with other output formats.

## Testing¶

There are various make targets to run tests easily:

• make test: run unit tests
• make test-examples: run full execution of the program, for a variety of input options
• make cov: run coverage.py and make a HTML report
• make benchmark: run performance metrics (mostly timing of components)

There are also various targets for linting, etc:

• make lint: run pylint
• make lint-py3: run pylint’s python3 checker Note this is not perfect!
• make flake: run flake8

Docs can be made locally by doing make docs.

## Conventions / Style¶

Lines should be < 100 lines, but sometimes going over makes more sense than horrible linebreaks. Try and fix all linter errors/warnings, but sometimes they are silly. Use Numpy-style for docstrings. All code should be compatible with python 2.7 and >=3.4. The compatibilty with 2.7 is because a significant proportion of HEP is still forced to use it, but at the same time we should forsee migration to python 3.