Avoid setattr/getattr with fixed format cache#20826
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ilevkivskyi merged 3 commits intopython:masterfrom Feb 16, 2026
Merged
Avoid setattr/getattr with fixed format cache#20826ilevkivskyi merged 3 commits intopython:masterfrom
ilevkivskyi merged 3 commits intopython:masterfrom
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JukkaL
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Feb 16, 2026
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Makes sense, the new code should be significantly more efficient when compiled.
mypy/nodes.py
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| setattr(node, flag, True) | ||
| def read_flags(data: ReadBuffer, num_flags: int) -> list[bool]: | ||
| packed = read_int(data) | ||
| return [packed & 1 << i != 0 for i in range(num_flags)] |
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Add parenthesees, since the precedence is otherwise a bit hard to see.
mypy/nodes.py
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| setattr(node, flag, True) | ||
| def read_flags(data: ReadBuffer, num_flags: int) -> list[bool]: | ||
| packed = read_int(data) | ||
| return [packed & 1 << i != 0 for i in range(num_flags)] |
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Use explicit parentheses to make precedence more obvious?
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
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This is a small optimization, and something that bothered me for a while. I write bit packing in Python because we have mypyc and we should use it (it should write relatively efficient code for this). Implementation is really basic, I only allow at most 26 flags, which will hopefully be enough for few years. Btw
Varhas 21 flags, I am quite sure some of those can be cleaned up.