Python CSS HTML Using % and .format() for great good!

With this project @ulope and @zerok wanted to document Python's awesome string formatting system with practical examples. While the official documentation on contains a great deal of information regarding the actual syntax specification of the formatters and some examples, we felt it would be nice to see the new and old style of formatting side-by-side and provide even more practical examples.

What is Where?

The website you can find on is statically generated using the This script parses the test cases specified in tests/ which is more or less where all the content of the final site comes from.

Each test case can consist of following elements:

  • A optional title which is encoded as the first line of the docstring prefixed with a #
  • A short description on what is going on in the example which is what the rest of the docstring is used for
  • A value computation for the old-style formatter which is assigned to a variable called old_result
  • A value computation for the new-style formatter which is assigned to a variable called new_result
  • A handful of assertions. The last one that has a string on the right side is used as output on the website.
  • An optional setup section that is placed after the docstring and before the old_result asignment

If no old_result is provided this indicates that the feature is only available for the new formatting style and an appropriate message is rendered on the website.

How to Contribute

If you have another awesome example of what can be done with Python's formatters please create a new test-case in tests/ including a short info message about what is going on there as the docstring.

Once you have that, simply open a pull-request! Please make sure that you code is PEP8-compliant (except for the line length).

Running the tests

We use py.test to both test the functionality of the script generating the static HTML output as well as ensuring that the examples on the page are syntactically correct and produce the desired output.

The easiest way to run the tests on all supported Python versions is by using tox for which this repository contains a configuration file.