pyrefact 42

Automatic python refactoring

# pyrefact Automatic python refactoring, with the goal of simplifying complicated code, deleting dead code, and to some extent improve performance.

It is strongly recommended that you version control or otherwise backup any code you run pyrefact on.

## Features

### Imports

• Delete unused imports

• Move safe imports to toplevel

• Add missing imports by guessing what you probably wanted. * For example, if Sequence is used but never defined, it will insert from typing import Sequence at the top of the file.

### Readability

• Rename variables, functions and classes with conventions.

### Removing dead and useless code

• Delete unused functions, classes and variables.

• Remove most pointless simple statements.

• Remove branches of code that obviously do nothing useful.

• Remove unreachable code.

• Rename unused variables to _

• Delete variables named _, unless where that would cause a syntax error.

• Remove redundant chained calls involving sorted(), set(), tuple(), reversed(), iter() and list().

• Remove duplicate function definitions.

• Remove redundant elif and else.

• Remove unused self and cls function arguments, and add @staticmethod or @classmethod.

• Move functions decorated with @staticmethod outside of their class namespaces.

### Performance

• Replace hardcoded inlined collections and comprehensions with set or generator equivalents in places where that would improve performance.

• Replace sorted()[:n] with heapq.nsmallest, replace sorted()[0] with min

• Use is for comparisons to None, True and False instead of ==.

• Replace math comprehensions and for loops with constant expressions. The symbolic algebra tool [Sympy](https://github.com/sympy/sympy) is used under the hood for this.

### Restructuring

• Move code into primitive functions.

• Invert if/else to put the smaller block first.

• De-indent code with early continue and return statements.

• Replace loops that only fill up lists or sets with comprehensions.

### Cleanup

• Run black and isort with –line-length=100. (Will be removed in a future release)

## Usage

The –preserve flag lets you define places where code is used. When this is set, pyrefact will try to keep these usages intact. The –safe flag will entirely prevent pyrefact from renaming or removing code. The –from-stdin flag will format code recieved from stdin, and output the result to stdout.

`bash pip install pyrefact python -m pyrefact /path/to/filename.py --preserve /path/to/module/where/filename/is/used python -m pyrefact /path/to/filename.py --safe cat /path/to/filename.py | pyrefact --from-stdin `

## Prerequisites

Pyrefact requires python>=3.8, and is tested on 3.8, 3.9, 3.10 and 3.11. Pyrefact works best on python>=3.9.