Question 1

How to create a custom refactoring pattern in Undebt?

Accepted Answer

To create a custom pattern, write a Python file with a grammar definition and a replace function, using utilities from the pattern files documentation. Start by studying examples like class_inherit_object.py to understand the token-based structure and syntax.

Question 2

Undebt vs jscodeshift: which is better for JavaScript refactoring?

Accepted Answer

Undebt is more flexible with custom Python patterns but is Python-centric, while jscodeshift is specifically designed for JavaScript with a built-in AST. For JavaScript projects, jscodeshift is often easier due to native support, but Undebt could be used with custom tokenizers if needed.

Question 3

Can Undebt handle multiple programming languages?

Accepted Answer

In theory, yes, but in practice, it's best suited for Python because the tokenization utilities and examples are tailored to it. For other languages, you'd need to define custom tokenizers, which can be challenging and less documented.

Question 4

What's the performance like when running Undebt on a large codebase?

Accepted Answer

Undebt is optimized for speed and can handle millions of lines efficiently, as shown in Yelp's use case. However, performance depends on pattern complexity and file size; tokenization might add overhead compared to simpler text tools.

Question 5

Are there pre-made patterns available for common tasks?

Accepted Answer

Only a limited set of examples are provided in the documentation, such as for Python class conversions. There's no extensive community repository, so users typically need to develop their own patterns from scratch.

Question 6

How to test an Undebt pattern before applying changes?

Accepted Answer

Use the command line to output changes to a file or combine with Unix utilities for review, as suggested in the tips and tricks documentation. Dry-run modes aren't explicitly built-in, but you can simulate by checking output without writing files.

Undebt

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