Refactor
Simple, hassle-free, dependency-free, AST based source code refactoring toolkit.
Why? How?
refactor is an end-to-end refactoring framework that is built on top
of the 'simple but effective refactorings' assumption. It is much easier
to write a simple script with it rather than trying to figure out what
sort of a regex you need in order to replace a pattern (if it is even
matchable with regexes).
Every refactoring rule offers a single entrypoint, match(), where they
accept an AST node (from the ast module in the standard library) and
respond with either returning an action to refactor or nothing. If the
rule succeeds on the input, then the returned action will build a
replacement node and refactor will simply replace the code segment
that belong to the input with the new version.
Here is a complete script that will replace every placeholder access
with 42 (not the definitions) on the given list of files:
import ast
from refactor import Rule, ReplacementAction, run
class Replace(Rule):
def match(self, node):
assert isinstance(node, ast.Name)
assert node.id == 'placeholder'
replacement = ast.Constant(42)
return ReplacementAction(node, replacement)
if __name__ == "__main__":
run(rules=[Replace])If we run this on a file, refactor will print the diff by default;
--- test_file.py
+++ test_file.py
@@ -1,11 +1,11 @@
def main():
- print(placeholder * 3 + 2)
- print(2 + placeholder + 3)
+ print(42 * 3 + 2)
+ print(2 + 42 + 3)
# some commments
- placeholder # maybe other comments
+ 42 # maybe other comments
if something:
other_thing
- print(placeholder)
+ print(42)
if __name__ == "__main__":
main()As stated above, refactor's scope is usually small stuff, so if you want to do full program transformations we highly advise you to look at CST-based solutions like parso, LibCST and Fixit