Add type hints to the codebase?

lcosmin · 06-02-2025, 01:39 AM

What's the take on adding type hints to the codebase?

I noticed they're lacking (at least in the parts I looked over) and I was thinking of adding them (in small, incremental changes, of course), as they can be very benefic in detecting various bugs.

But I wanted to confirm first that this is something wanted, so that I don't wase time in vain.

kovidgoyal · 06-02-2025, 11:25 AM

You are welcome to work on it if you feel like it, IME they are not worth the bother for a codebase as large and complex and mature and, dare I say it, as bug free as calibre. They will catch no more than 10% of real bugs for what is quite a large effort.

That said as long as your PRs come in a size that is reasonable to review and dont change any actual code, only add annotations, I will be willing to merge. But be aware this is a million line codebase. So unless you are willing to commit a few man months possibly a man year to it, you wont get anywhere useful.

I would suggest you identify some subsystem and work on making that type check first. go subsystem by subsystem

lcosmin · 06-02-2025, 04:38 PM

After going through many lines of code, I'm starting to agree that adding type hints is not worth the time.

Not that they're not useful, but the codebase would rather benefit from more serious modernization (e.g. cleanup, refactoring) than just type hints. And that's quite a big effort.

06-02-2025, 01:39 AM	#1
lcosmin Junior Member Posts: 2 Karma: 10 Join Date: Jun 2025 Device: Kobo Libra Color	Add type hints to the codebase? What's the take on adding type hints to the codebase? I noticed they're lacking (at least in the parts I looked over) and I was thinking of adding them (in small, incremental changes, of course), as they can be very benefic in detecting various bugs. But I wanted to confirm first that this is something wanted, so that I don't wase time in vain.

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06-02-2025, 11:25 AM	#2
kovidgoyal creator of calibre Posts: 45,251 Karma: 27110894 Join Date: Oct 2006 Location: Mumbai, India Device: Various	You are welcome to work on it if you feel like it, IME they are not worth the bother for a codebase as large and complex and mature and, dare I say it, as bug free as calibre. They will catch no more than 10% of real bugs for what is quite a large effort. That said as long as your PRs come in a size that is reasonable to review and dont change any actual code, only add annotations, I will be willing to merge. But be aware this is a million line codebase. So unless you are willing to commit a few man months possibly a man year to it, you wont get anywhere useful. I would suggest you identify some subsystem and work on making that type check first. go subsystem by subsystem

06-02-2025, 04:38 PM	#3
lcosmin Junior Member Posts: 2 Karma: 10 Join Date: Jun 2025 Device: Kobo Libra Color	After going through many lines of code, I'm starting to agree that adding type hints is not worth the time. Not that they're not useful, but the codebase would rather benefit from more serious modernization (e.g. cleanup, refactoring) than just type hints. And that's quite a big effort.

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