[vstinner]

• Rename _PyList_AsTupleAndClear() to PyList_AsTupleAndClear().
• The function now raises TypeError if the argument is not a list.
• Add documentation and tests.

• Issue: [C API] Add PyList_AsTupleAndClear() function #161635

[read-the-docs-community]

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± c-api/list.html
± whatsnew/3.16.html
± whatsnew/changelog.html

[sobolevn]

Great stuff! This would be useful for us in msgspec's type convertion :)

[sobolevn]

question: is () being a singleton a contract or implementation detail? if the former, it would be better to compare the equality.

[vstinner]

Ah, that's a tricky question. It's more an implementation detail. But I would like to test this implementation detail, to check that we don't loose this optimization in a future refatoring.

[sobolevn]

@vstinner should we do the same with PySet_AsFrozenSetAndClear()?

[vstinner]

@vstinner should we do the same with PySet_AsFrozenSetAndClear()?

I found a few functions calling PyFrozenSet_New(iterable) and then discards iterable:

• _PyCode_ConstantKey(): from tuple
• make_union(): from set
• load_frozenset(): from tuple

So only make_union() with its unionbuilder API may benefit from adding a PySet_AsFrozenSetAndClear() function. Maybe we can start by adding a private function? Do you want to add such private function?

I'm not sure that it's worth it to add a public PySet_AsFrozenSetAndClear() function right now.

... Also, I'm working on PyFrozenSetWriter API which should cover more use cases: #160154 :-)

[sobolevn]

Do you want to add such private function?

No, I would prefer to have a well-designed public API :)
PyFrozenSetWriter seems promising! 🎉