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interfaces: introduce and use a protocol class for the `bdiff` module...
interfaces: introduce and use a protocol class for the `bdiff` module This is allowed by PEP 544[1], and we basically follow the example there. The class here is copied from `mercurial.pure.bdiff`, and the implementation removed. There are several modules that have a few different implementations, and the implementation chosen is controlled by `HGMODULEPOLICY`. The module is loaded via `mercurial/policy.py`, and has been inferred by pytype as `Any` up to this point. Therefore it and PyCharm were blind to all functions on the module, and their signatures. Also, having multiple instances of the same module allows their signatures to get out of sync. Introducing a protocol class allows the loaded module that is stored in a variable to be given type info, which cascades through the various places it is used. This change alters 11 *.pyi files, for example. In theory, this would also allow us to ensure the various implementations of the same module are kept in alignment- simply import the module in a test module, attempt to pass it to a function that uses the corresponding protocol as an argument, and run pytype on it. In practice, this doesn't work (yet). PyCharm (erroneously) flags imported modules being passed where a protocol class is used[2]. Pytype has problems the other way- it fails to detect when a module that doesn't adhere to the protocol is passed to a protocol argument. The good news is that mypy properly detects this case. The bad news is that mypy spews a bunch of other errors when importing even simple modules, like the various `bdiff` modules. Therefore I'm punting on the tests for now because the type info around a loaded module in PyCharm is a clear win by itself. [1] https://peps.python.org/pep-0544/#modules-as-implementations-of-protocols [2] https://youtrack.jetbrains.com/issue/PY-58679/Support-modules-implementing-protocols

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sequence.py
163 lines | 4.6 KiB | text/x-python | PythonLexer
##############################################################################
#
# Copyright (c) 2001, 2002 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Sequence Interfaces
"""
from __future__ import absolute_import
__docformat__ = 'restructuredtext'
from .. import Interface
class IMinimalSequence(Interface):
"""Most basic sequence interface.
All sequences are iterable. This requires at least one of the
following:
- a `__getitem__()` method that takes a single argument; interger
values starting at 0 must be supported, and `IndexError` should
be raised for the first index for which there is no value, or
- an `__iter__()` method that returns an iterator as defined in
the Python documentation (http://docs.python.org/lib/typeiter.html).
"""
def __getitem__(index):
"""`x.__getitem__(index)` <==> `x[index]`
Declaring this interface does not specify whether `__getitem__`
supports slice objects."""
class IFiniteSequence(IMinimalSequence):
def __len__():
"""`x.__len__()` <==> `len(x)`"""
class IReadSequence(IFiniteSequence):
"""read interface shared by tuple and list"""
def __contains__(item):
"""`x.__contains__(item)` <==> `item in x`"""
def __lt__(other):
"""`x.__lt__(other)` <==> `x < other`"""
def __le__(other):
"""`x.__le__(other)` <==> `x <= other`"""
def __eq__(other):
"""`x.__eq__(other)` <==> `x == other`"""
def __ne__(other):
"""`x.__ne__(other)` <==> `x != other`"""
def __gt__(other):
"""`x.__gt__(other)` <==> `x > other`"""
def __ge__(other):
"""`x.__ge__(other)` <==> `x >= other`"""
def __add__(other):
"""`x.__add__(other)` <==> `x + other`"""
def __mul__(n):
"""`x.__mul__(n)` <==> `x * n`"""
def __rmul__(n):
"""`x.__rmul__(n)` <==> `n * x`"""
def __getslice__(i, j):
"""`x.__getslice__(i, j)` <==> `x[i:j]`
Use of negative indices is not supported.
Deprecated since Python 2.0 but still a part of `UserList`.
"""
class IExtendedReadSequence(IReadSequence):
"""Full read interface for lists"""
def count(item):
"""Return number of occurrences of value"""
def index(item, *args):
"""Return first index of value
`L.index(value, [start, [stop]])` -> integer"""
class IUniqueMemberWriteSequence(Interface):
"""The write contract for a sequence that may enforce unique members"""
def __setitem__(index, item):
"""`x.__setitem__(index, item)` <==> `x[index] = item`
Declaring this interface does not specify whether `__setitem__`
supports slice objects.
"""
def __delitem__(index):
"""`x.__delitem__(index)` <==> `del x[index]`
Declaring this interface does not specify whether `__delitem__`
supports slice objects.
"""
def __setslice__(i, j, other):
"""`x.__setslice__(i, j, other)` <==> `x[i:j]=other`
Use of negative indices is not supported.
Deprecated since Python 2.0 but still a part of `UserList`.
"""
def __delslice__(i, j):
"""`x.__delslice__(i, j)` <==> `del x[i:j]`
Use of negative indices is not supported.
Deprecated since Python 2.0 but still a part of `UserList`.
"""
def __iadd__(y):
"""`x.__iadd__(y)` <==> `x += y`"""
def append(item):
"""Append item to end"""
def insert(index, item):
"""Insert item before index"""
def pop(index=-1):
"""Remove and return item at index (default last)"""
def remove(item):
"""Remove first occurrence of value"""
def reverse():
"""Reverse *IN PLACE*"""
def sort(cmpfunc=None):
"""Stable sort *IN PLACE*; `cmpfunc(x, y)` -> -1, 0, 1"""
def extend(iterable):
"""Extend list by appending elements from the iterable"""
class IWriteSequence(IUniqueMemberWriteSequence):
"""Full write contract for sequences"""
def __imul__(n):
"""`x.__imul__(n)` <==> `x *= n`"""
class ISequence(IReadSequence, IWriteSequence):
"""Full sequence contract"""