apply_generic_arguments: replace runtime checks with assertions #2346
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elazarg
commented
Oct 27, 2016
| msg = messages.temp_message_builder() | ||
| applied = mypy.applytype.apply_generic_arguments(type, inferred_vars, msg, context=target) | ||
| if msg.is_errors() or not isinstance(applied, CallableType): | ||
| if msg.is_errors(): |
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Perhaps msg.is_errors() should be an assertion too?
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I doubt it, unless you can prove that apply_generic_arguments() cannot produce any errors.
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It definitely can produce errors, since it checks type variable bounds/allowed values.
gvanrossum
reviewed
Oct 27, 2016
mypy/applytype.py
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| 'def (int) -> int'. | ||
| Note that each type can be None; in this case, it will not be applied. | ||
| Can only be None when len(tvars) != len(types) |
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Yes it's outdated. Thanks.
gvanrossum
reviewed
Oct 27, 2016
mypy/applytype.py
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| Note that each type can be None; in this case, it will not be applied. | ||
| Can only be None when len(tvars) != len(types) | ||
| """ | ||
| assert len(callable.variables) == len(types) |
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I'd move the assert after the assignment.
mypy/applytype.py
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| Note that each type can be None; in this case, it will not be applied. | ||
| Can only be None when len(tvars) != len(types) | ||
| """ | ||
| assert len(callable.variables) == len(types) |
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I'd move the assert after the assignment.
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Thanks! |
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Part of #2272.
The only place where the number of type arguments in type application might not match is when the user does that; this is explicitly checked in
visit_type_application. Other places involve type inference, which must be correct "by construction" and if it isn't, that's a bug we want to catch, instead of returning AnyType.It also allows us to remove casts.
cc @ddfisher