str.translate caching values causes incorrect result #144463
Description
Bug report
Bug description:
It seems that str.translate is caching values internally and this is causing unintended results.
When the translation table returns an ordinal or a string ordinal string, it caches the values returned by __getitem__ and will not call the function again. However if you are returning a 2-length string this doesn't occur (and in fact calls __getitem__ an additional time for some reason?).
I expect that the __getitem__ be executed for every character since the function documentation does not mention this caching value and more-so the function behaves inconsistently.
This is likely caused by #65317.
class counting_translate_ord(dict[int, int]):
def __init__(self) -> None:
super().__init__()
self.missing_calls = 0
def __getitem__(self, key: int) -> int:
self.missing_calls += 1
return ord(str(self.missing_calls % 10))
table = counting_translate_ord()
print(("----").translate(table)) # 1111
print(table.missing_calls) # 1
print(("!@#$").translate(table)) # 2345
print(table.missing_calls) # 5
class counting_translate_str(dict[int, str]):
def __init__(self) -> None:
super().__init__()
self.missing_calls = 0
def __getitem__(self, key: int) -> str:
self.missing_calls += 1
return str(self.missing_calls % 10)
table = counting_translate_str()
print(("----").translate(table)) # 1111
print(table.missing_calls) # 1
print(("!@#$").translate(table)) # 2345
print(table.missing_calls) # 5
class counting_translate_2str(dict[int, str]):
def __init__(self) -> None:
super().__init__()
self.missing_calls = 0
def __getitem__(self, key: int) -> str:
self.missing_calls += 1
return format(self.missing_calls, "02d")[:2]
table = counting_translate_2str()
print(("----").translate(table)) # 02030405
print(table.missing_calls) # 5
print(("!@#$").translate(table)) # 07080910
print(table.missing_calls) # 10CPython versions tested on:
3.12
Operating systems tested on:
Linux