Coding best practices

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  There are code standards and conventions available depending on the language you are using and sometimes also conventions adopted for specific collaborative projects. While below we provide a few links to these, here we are just going to focus on some basic tips that can help you making your code more readable and safer from bugs. These can be applied to any language.   Use long and descriptive names for variables and functions   There is no anymore reason to use short names for variables and functions, it is good practice instead to use names that are descriptive, even if this will make them longer. Particularly for functions it is good to specify in the name what they do Ex for a function that calculates an anomaly use calculate_anomaly() rather than calc(). This also reduce the chances of using a reserved word** NB If you're using an IDE to edit your code then you can auto complete the names   **reserved words Use consistent naming across the code Try to be consistent in the way you name your variable, constants and functions. There are a few conventions out there among the most common:

  • lowercase_words_with_underscores,
  • CapitalisedWords (also known as CamelCase),
  • ALL_CAPITALS for constants values 
  • mixedCase

Whatever you choose try to be consistent, use the same conventions for the same type of objects.   Indents   Some languages like Python enforce indenting, but even where it is not necessary indenting your code can help outlining the code structure. Again try to be consistent either use tabs or spaces, some languages like python have a preference for spaces.   Comments Comments are extremely useful to document what your code is doing. Again you do not need to comment every line, as that might actually made the code less redable. But it is a good practice to have:

  •  a block of comments at the start of the code listing author, license,a a date for the last update, what the code does and how to use it.
  • similarly have a fe wlines of comments for each function or before a coherent block of code in the main program, for example before an "if/else" block.

It can also be useful starting a code by writing what do you want to do as comments. For example   # Assign arguments # Open data files # Calculate ... # Plot ... # Save output to file

  In this way you have a draft of your comments and you can work out the best structure, indivifduate blocks that can be included ina. function etc, before you even start coding. It can save you a lot of time.   Subdive your code using functions or sub-modules   Ideally a function should execute one coherent operation. As none of us it's a software developer we are not suggesting every line of code is a function , more than a logical block of lines should be included in a function. This is particularly true and useful if it's a block of code you might want to repeat in other parts of this same or others programs. Another good reason to enclose a block of code in a function it is to make it easier to add a test.   Use tests   It is a good idea to test at least critical parts of your code. You want to be sure that a calculation which is critical to your results, is producing consistent and correct results, no matter what changes you introduce to the same function or other part of your code. No matter how many tests you are conducting it is hard to preview all the possible ways a code can be used and it is often the case that as soon as you sue a different set of data you are going to find some bugs. Every time you fix a bug make sure you are adding a test to capture it. So you will know if accidentally you re-introduce it later on.

Standards:

  https://www.python.org/dev/peps/pep-0008/   Main message here is to be consistent and descriptive, in the end any conventions aim is to have consistency. Even if you are not using an established convention, being at least consistent across all of your codes will help making them more readable and re-usable.   References This page was inspired by the seminar "Reproducible research how to write code that is built to last organised by DataTas. A recording is available on their facebook page.