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_setattr_cached = object.__setattr__

class A:
    __slots__ = ('x', 'y', 'z', 'a', 'b', 'c')

    def __init__(self, x, y, z, a, b, c):
        _setattr = _setattr_cached.__get__(self, A)
        _setattr('x', x)
        _setattr('y', y)
        _setattr('z', z)

Tinche

import attr
import pickle


@attr.s(frozen=True)
class A(object):
    x = attr.ib()

@attr.s(slots=True)
class B(object):

Tinche

from hypothesis.stateful import RuleBasedStateMachine, run_state_machine_as_test, rule, precondition

def test_t():
    class StatefulTest(RuleBasedStateMachine):
        def __init__(self):
            print("init")
            super().__init__()
            self.a = False
            self.b = False
            self.c = False

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>>> msgpack.loads(msgpack.dumps(b"TEST", encoding='utf8', use_bin_type=True), encoding='utf8')
b'TEST'
>>> msgpack.loads(msgpack.dumps("TEST", encoding='utf8', use_bin_type=True), encoding='utf8')
'TEST'

Tinche

from cpython.object cimport descrgetfunc, Py_TYPE


cdef class FrozenSlotDescriptor(object):
    """
    Wraps the normal Python slot descriptor, disabling write access.
    """
    cdef descrgetfunc get
    cdef object descriptor
    def __cinit__(self, orig):

Tinche

import pyximport; pyximport.install()
from frozen import FrozenSlotDescriptor


class A(object):
    __slots__ = ('a',)


A._old = A.a
A.a = FrozenSlotDescriptor(A.a)

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from attr._make import _attrs_to_tuple as attrs_to_tuple

class A:
    def __init__(self, a):
        self.a = a
    def __eq__(self, other):
        """
        Automatically created by attrs.
        """
        if other.__class__ is self.__class__:

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========================================================================================================================== FAILURES ===========================================================================================================================
_________________________________________________________________________________________________________________________ test_lists __________________________________________________________________________________________________________________________

    def test_lists():
>       assert [i for i in range(20)] == [i for i in range(21)]
E       assert [0, 1, 2, 3, 4, 5, ...] == [0, 1, 2, 3, 4, 5, ...]
E         Right contains more items, first extra item: 20
E         Full diff:
E         - [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
E         + [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]

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> pyperf timeit -g -s "i = [(e, 1) for e in range(1000)]" "[e[0] for e in i]"
.....................
39.5 us: 1 ###########
39.6 us: 2 #######################
39.7 us: 4 #############################################
39.9 us: 6 ####################################################################
40.0 us: 6 ####################################################################
40.1 us: 7 ###############################################################################
40.2 us: 6 ####################################################################
40.3 us: 6 ####################################################################

Tinche

import attr

@attr.s
class C:
    a = attr.ib()
    
    __hash__ = attr.hash_by_values