Craftier

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      Your personal Python code reviewer

What is it?

Craftier is a framework to easily writing Python code refactors. In the near future it will also come with a set of predefined refactoring rules.

It is based on libcst and simplifies the use of its API by letting you write refactors just by writing Python code.

It also preserves relevant comments and ensures the modified code is correct, by adding required parentheses.

Getting started

After installing with pip install craftier, you can run the default rules with craftier refactor <python files>.

Configuration

By default we look for a .craftier.ini, if none is found a default configuration will be used.

You can also specify the config file with --config CONFIG_PATH

Config format

[craftier]
packages=craftier.refactors,
excluded=A,
         B

Writing your own rules

As simple as:

import craftier

class SquareTransformer(craftier.CraftierTransformer):
    def square_before(self, x):
        x * x

    def square_after(self, x):
        x ** 2


class IfTrueTransformer(craftier.CraftierTransformer):
    def if_true_before(self, x, y):
        x if True else y

    def if_true_after(self, x):
        x

TODO: write about custom matchers and type declarations

Roadmap and TODOs

• Support multiple expressions in a transformer
• Add support for statements
• Complete set of refactorings
• Add support for typing metadata
• Generate RE2 filtering based on expressions. This could be used to prefilter the list of files and to test the patterns either in codebase search tools like https://grep.app
• Extensive validation testing

Limitations

This is a work in progress, and some edges are rough.

Given that we match code based on actual Python code, some refactorings are not easily expressed or may not even be expressible at all.

History

TODO: write how I came up with the idea.

Name

Originally I wanted to name this package pythonista, but unfortunately someone squatted the name (along with several others) and the name was not released according to procedure. Furthermore, the issue was locked.

That gave me a chance of rethinking the name, so I started with anagrams of the word refactor, which was of course unsuccessful. So after some experimentation I replaced the letter o with an i, giving refactir, which is an anagram of the word craftier.

I like that name, because is like a "refactoring" of the word refactor, and craftier conveys the actual use case of the tool.

Bonus: the name sounds somewhat like my surname.