refactor 0.1.0a0

AST based source code refactor interface

Refactor

Simple, dependency-free, AST based source code refactoring interface.

:warning: This project is still work-in-progress: Be very careful with depending on the APIs!

How

refactor is nothing more than a tiny wrapper around your AST processing code. Each refactor operation is a rule (refactor.Rule) where they return either an action (refactor.Action) to translate or None from their match method.

Here is an example rule that replaces all placeholders with 42. The ReplacementAction is a subclass of refactor.Action, which takes the original node and the replacement node and changes the segment belonging the initial node with the unparsed version of other.

import ast
import refactor
from refactor import Rule, ReplacementAction

class ReplacePlaceholders(Rule):

    def match(self, node):
        assert isinstance(node, ast.Name)
        assert isinstance(node.ctx, ast.Load)
        assert node.id == "placeholder"

        replacement = ast.Constant(42)
        return ReplacementAction(node, replacement)

if __name__ == "__main__":
    refactor.run(rules=[ReplacePlaceholders])

The refactor package comes bundled with a simple entry point generator, which can be used through simply running refactor.run() with the rules you want to apply. It will create a CLI application which takes files and outputs diffs. Here is an example file that we might test the following script;

def test():
    print(placeholder)
    print( # complicated
        placeholder
    )
    if placeholder is placeholder or placeholder > 32:
        print(3  + placeholder)

And if we run the refactor script;

--- examples/test/placeholder.py

+++ examples/test/placeholder.py

@@ -1,8 +1,7 @@

 def test():
-    print(placeholder)
+    print(42)
     print( # complicated
-        placeholder
+        42
     )
-    if placeholder is placeholder or placeholder > 32:
-        print(3  + placeholder)
-
+    if 42 is 42 or 42 > 32:
+        print(3  + 42)