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interfaces: add the optional `bdiff.xdiffblocks()` method...
interfaces: add the optional `bdiff.xdiffblocks()` method PyCharm flagged where this was called on the protocol class in `mdiff.py` in the previous commit, but pytype completely missed it. PyCharm is correct here, but I'm committing this separately to highlight this potential problem- some of the implementations don't implement _all_ of the methods the others do, and there's not a great way to indicate on a protocol class that a method or attribute is optional- that's kinda the opposite of what static typing is about. Making the method an `Optional[Callable]` attribute works here, and keeps both PyCharm and pytype happy, and the generated `mdiff.pyi` and `modules.pyi` look reasonable. We might be getting a little lucky, because the method isn't invoked directly- it is returned from another method that selects which block function to use. Except since it is declared on the protocol class, every module needs this attribute (in theory, but in practice this doesn't seem to be checked), so the check for it on the module has to change from `hasattr()` to `getattr(..., None)`. We defer defining the optional attrs to the type checking phase as an extra precaution- that way it isn't an attr with a `None` value at runtime if someone is still using `hasattr()`. As to why pytype missed this, I have no clue. The generated `mdiff.pyi` even has the global variable typed as `bdiff: intmod.BDiff`, so uses of it really should comply with what is on the class, protocol class or not.

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setters.py
73 lines | 1.4 KiB | text/x-python | PythonLexer
# SPDX-License-Identifier: MIT
"""
Commonly used hooks for on_setattr.
"""
from . import _config
from .exceptions import FrozenAttributeError
def pipe(*setters):
"""
Run all *setters* and return the return value of the last one.
.. versionadded:: 20.1.0
"""
def wrapped_pipe(instance, attrib, new_value):
rv = new_value
for setter in setters:
rv = setter(instance, attrib, rv)
return rv
return wrapped_pipe
def frozen(_, __, ___):
"""
Prevent an attribute to be modified.
.. versionadded:: 20.1.0
"""
raise FrozenAttributeError()
def validate(instance, attrib, new_value):
"""
Run *attrib*'s validator on *new_value* if it has one.
.. versionadded:: 20.1.0
"""
if _config._run_validators is False:
return new_value
v = attrib.validator
if not v:
return new_value
v(instance, attrib, new_value)
return new_value
def convert(instance, attrib, new_value):
"""
Run *attrib*'s converter -- if it has one -- on *new_value* and return the
result.
.. versionadded:: 20.1.0
"""
c = attrib.converter
if c:
return c(new_value)
return new_value
# Sentinel for disabling class-wide *on_setattr* hooks for certain attributes.
# autodata stopped working, so the docstring is inlined in the API docs.
NO_OP = object()