What is a good tool interface to apply file updates (patches)?

[georgeu2000]

After working with OpenAI API and Claude 3.7 and defining my own tools, it never knows the correct line number (even if I provide the file with line numbers).

Matching lines does not work so well because of duplicates.

Clearly this is a well-solved problem.

What is the best practice to do file updates? Does Ruby LLM handle this?

[db0sch]

I've been working on the same problem.
And yet, the LLM does not know the lines number. Mostly cause the whole thing is a big ball of text, with text before and after (prompts). You can't rely on the line numbers.
What you must do:
Write a tool that takes 3 parameters:

• file_path
• old_string
• new_string

And in the description of the old_string, specify that the old_string must be unique in the text, and to do that, It should take a couple of lines before and couple of lines after what it actually wants to change, to compose the old_string. That way, in your tool, you can simply gsub the original text with the old_string and the new_string. No line numbers. Just text matching.

Does this make sense for you?

PS: and no, RubyLLM does not takes care of this. This is really the job of the internal implementation of your tool :)

[georgeu2000]

OK, that sounds like it would work. Thanks.

[db0sch]

Just FYI, I've investigated this a bit.
And that's how some file editing MCPs do it, and also, that's how Zed editor agent does it: https://github.com/zed-industries/zed
Also, you should read this blog post :)
https://radanskoric.com/articles/coding-agent-in-ruby

[georgeu2000]

I read the blog post. That's how I found out about Ruby LLM, haha.