Remove the 'rop will not be called' error message #5571
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python#5475 introduced a new type of error message ("__rop__ will not be called when evaluating 'a + b'...") that triggers when the user tries evaluating expressions like `foo + foo` where `foo` does not contain an `__add__` method that accepts a value of the same type, but *does* contain an `__radd__` method that does. This pull request removes that error message on the grounds that it's too cryptic and unlikely to be helpful to most mypy users. That error message is useful mainly for people developing libraries containing custom numeric types (or libraries that appropriate operators to create custom DSLs) -- however, most people are not library creators and so will not find this error message useful.
ilevkivskyi
approved these changes
Sep 5, 2018
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OK, I was thinking maybe we can keep this error if it appears for classes defined in user code, but t hen it is very hard to decide what is user code, so probably just removing the note is a right solution.
Anyway, most likely the code flagged with error will fail at runtime.
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#5475 introduced a new type of error message ("rop will not be called when evaluating 'a + b'...") that triggers when the user tries evaluating expressions like
foo + foowherefoodoes not contain an__add__method that accepts a value of the same type, but does contain an__radd__method that does.This pull request removes that error message on the grounds that it's too cryptic and unlikely to be helpful to most mypy users. That error message is useful mainly for people developing libraries containing custom numeric types (or libraries that appropriate operators to create custom DSLs) -- however, most people are not library creators and so will not find this error message useful.