diff -r a824c40e8fc0 -r d69c5520c617 Doc/reference/expressions.rst --- a/Doc/reference/expressions.rst Sat Feb 21 15:26:02 2015 -0800 +++ b/Doc/reference/expressions.rst Mon Mar 02 19:02:13 2015 +0100 @@ -1021,10 +1021,6 @@ .. _comparisons: -.. _is: -.. _is not: -.. _in: -.. _not in: Comparisons =========== @@ -1060,66 +1056,182 @@ *c*, so that, e.g., ``x < y > z`` is perfectly legal (though perhaps not pretty). +Value comparisons +----------------- + The operators ``<``, ``>``, ``==``, ``>=``, ``<=``, and ``!=`` compare the -values of two objects. The objects need not have the same type. If both are -numbers, they are converted to a common type. Otherwise, the ``==`` and ``!=`` -operators *always* consider objects of different types to be unequal, while the -``<``, ``>``, ``>=`` and ``<=`` operators raise a :exc:`TypeError` when -comparing objects of different types that do not implement these operators for -the given pair of types. You can control comparison behavior of objects of -non-built-in types by defining rich comparison methods like :meth:`__gt__`, -described in section :ref:`customization`. +values of two objects. The objects do not need to have the same type. -Comparison of objects of the same type depends on the type: +Chapter :ref:`objects` states that objects have a value (in addition to type +and identity). The value of an object is a rather abstract notion in Python: +For example, there is no canonical access method for an object's value. Also, +there is no requirement that the value of an object should be constructed in a +particular way, e.g. comprised of all its data attributes. Comparison operators +implement a particular notion of what the value of an object is. One can think +of them as defining the value of an object indirectly, by means of their +comparison implementation. -* Numbers are compared arithmetically. +Because all types are (direct or indirect) subtypes of :class:`object`, they +inherit the default comparison behavior from :class:`object`. Types can +customize their comparison behavior by implementing +:dfn:`rich comparison methods` like :meth:`__lt__`, described in +:ref:`customization`. -* The values :const:`float('NaN')` and :const:`Decimal('NaN')` are special. - They are identical to themselves, ``x is x`` but are not equal to themselves, - ``x != x``. Additionally, comparing any value to a not-a-number value +The default behavior for equality comparison (``==`` and ``!=``) is based on +the identity of the objects. Hence, equality comparison of instances with the +same identity results in equality, and equality comparison of instances with +different identities results in inequality. A motivation for this default +behavior is the desire that all objects should be reflexive (i.e. ``x is y`` +implies ``x == y``). + +A default order comparison (``<``, ``>``, ``<=``, and ``>=``) is not provided; +an attempt raises :exc:`TypeError`. A motivation for this default behavior is +the lack of a similar invariant as for equality. + +The behavior of the default equality comparison, that instances with different +identities are always unequal, may be in contrast to what types will need that +have a sensible definition of object value and value-based equality. Such +types will need to customize their comparison behavior, and in fact, a number +of built-in types have done that. + +The following list describes the comparison behavior of the most important +built-in types. + +* Numbers of built-in numeric types (:ref:`typesnumeric`) and of the standard + library types :class:`fractions.Fraction` and :class:`decimal.Decimal` can be + compared within and across their types, with the restriction that complex + numbers do not support order comparison. Within the limits of the types + involved, they compare mathematically (algorithmically) correct without loss + of precision. + + The not-a-number values :const:`float('NaN')` and :const:`Decimal('NaN')` + are special. They are identical to themselves (``x is x`` is true) but + are not equal to themselves (``x == x`` is false). Additionally, + comparing any number to a not-a-number value will return ``False``. For example, both ``3 < float('NaN')`` and ``float('NaN') < 3`` will return ``False``. -* Bytes objects are compared lexicographically using the numeric values of their - elements. +* Binary sequences (instances of :class:`bytes` or :class:`bytearray`) can be + compared within and across their types. They compare lexicographically using + the numeric values of their elements. -* Strings are compared lexicographically using the numeric equivalents (the - result of the built-in function :func:`ord`) of their characters. [#]_ String - and bytes object can't be compared! +* Strings (instances of :class:`str`) compare lexicographically using the + numerical Unicode code points (the result of the built-in function + :func:`ord`) of their characters. [#]_ -* Tuples and lists are compared lexicographically using comparison of - corresponding elements. This means that to compare equal, each element must - compare equal and the two sequences must be of the same type and have the same - length. + Strings and binary sequences cannot be directly compared. - If not equal, the sequences are ordered the same as their first differing - elements. For example, ``[1,2,x] <= [1,2,y]`` has the same value as - ``x <= y``. If the corresponding element does not exist, the shorter - sequence is ordered first (for example, ``[1,2] < [1,2,3]``). +* Sequences (instances of :class:`tuple`, :class:`list`, or :class:`range`) can + be compared only within each of their types, with the restriction that ranges + do not support order comparison. Equality comparison across these types + results in unequality, and ordering comparison across these types raises + :exc:`TypeError`. -* Mappings (dictionaries) compare equal if and only if they have the same - ``(key, value)`` pairs. Order comparisons ``('<', '<=', '>=', '>')`` - raise :exc:`TypeError`. + Sequences compare lexicographically using comparison of corresponding + elements, whereby reflexivity of the elements is enforced. -* Sets and frozensets define comparison operators to mean subset and superset - tests. Those relations do not define total orderings (the two sets ``{1,2}`` - and {2,3} are not equal, nor subsets of one another, nor supersets of one + In enforcing reflexivity of elements, the comparison of collections assumes + that for a collection element ``x``, ``x == x`` is always true. Based on + that assumption, element identity is compared first, and element comparison + is performed only for distinct elements. This approach yields the same + result as a strict element comparison would, if the compared elements are + reflexive. For non-reflexive elements, the result is different than for + strict element comparison, and may be surprising: The non-reflexive + not-a-number values for example result in the following comparison behavior + when used in a list:: + + >>> math.nan is math.nan + True + >>> math.nan == math.nan + False <-- the defined non-reflexive behavior of NaN + >>> [math.nan] == [math.nan] + True <-- list enforces reflexivity and tests identity first + + Lexicographical comparison between built-in collections works as follows: + + - For two collections to compare equal, they must be of the same type, have + the same length, and each pair of corresponding elements must compare + equal (for example, ``[1,2] == (1,2)`` is false because the type is not the + same). + + - Collections that support order comparison are ordered the same as their + first unequal elements (for example, ``[1,2,x] <= [1,2,y]`` has the same + value as ``x <= y``). If a corresponding element does not exist, the + shorter collection is ordered first (for example, ``[1,2] < [1,2,3]`` is + true). + +* Mappings (instances of :class:`dict`) compare equal if and only if they have + equal `(key, value)` pairs. Equality comparison of the keys and elements + enforces reflexivity. + + Order comparisons (``<``, ``>``, ``<=``, and ``>=``) raise :exc:`TypeError`. + +* Sets (instances of :class:`set` or :class:`frozenset`) can be compared within + and across their types. + + They define order + comparison operators to mean subset and superset tests. Those relations do + not define total orderings (for example, the two sets ``{1,2}`` and ``{2,3}`` + are not equal, nor subsets of one another, nor supersets of one another). Accordingly, sets are not appropriate arguments for functions - which depend on total ordering. For example, :func:`min`, :func:`max`, and - :func:`sorted` produce undefined results given a list of sets as inputs. + which depend on total ordering (for example, :func:`min`, :func:`max`, and + :func:`sorted` produce undefined results given a list of sets as inputs). -* Most other objects of built-in types compare unequal unless they are the same - object; the choice whether one object is considered smaller or larger than - another one is made arbitrarily but consistently within one execution of a - program. + Comparison of sets enforces reflexivity of its elements. -Comparison of objects of differing types depends on whether either of the -types provide explicit support for the comparison. Most numeric types can be -compared with one another. When cross-type comparison is not supported, the -comparison method returns ``NotImplemented``. +* Most other built-in types have no comparison methods implemented, so they + inherit the default comparison behavior. +User-defined classes that customize their comparison behavior should follow +some consistency rules, if possible: + +* Equality comparison should be reflexive. + In other words, identical objects should compare equal: + + ``x is y`` implies ``x == y`` + +* Comparison should be symmetric. + In other words, the following expressions should have the same result: + + ``x == y`` and ``y == x`` + + ``x != y`` and ``y != x`` + + ``x < y`` and ``y > x`` + + ``x <= y`` and ``y >= x`` + +* Comparison should be transitive. + The following (non-exhaustive) examples illustrate that: + + ``x > y and y > z`` implies ``x > z`` + + ``x < y and y <= z`` implies ``x < z`` + +* Inverse comparison should result in the boolean negation. + In other words, the following expressions should have the same result: + + ``x == y`` and ``not x != y`` + + ``x < y`` and ``not x >= y`` (for total ordering) + + ``x > y`` and ``not x <= y`` (for total ordering) + + The last two expressions apply to totally ordered collections (e.g. to + sequences, but not to sets or mappings). See also the + :func:`~functools.total_ordering` decorator. + +Python does not enforce these consistency rules. In fact, the not-a-number +values are an example for not following these rules. + + +.. _in: +.. _not in: .. _membership-test-details: +Membership test operations +-------------------------- + The operators :keyword:`in` and :keyword:`not in` test for membership. ``x in s`` evaluates to true if *x* is a member of *s*, and false otherwise. ``x not in s`` returns the negation of ``x in s``. All built-in sequences and set types @@ -1161,6 +1273,13 @@ operator: is not pair: identity; test + +.. _is: +.. _is not: + +Identity comparisons +-------------------- + The operators :keyword:`is` and :keyword:`is not` test for object identity: ``x is y`` is true if and only if *x* and *y* are the same object. ``x is not y`` yields the inverse truth value. [#]_ @@ -1388,12 +1507,24 @@ cases, Python returns the latter result, in order to preserve that ``divmod(x,y)[0] * y + x % y`` be very close to ``x``. -.. [#] While comparisons between strings make sense at the byte level, they may - be counter-intuitive to users. For example, the strings ``"\u00C7"`` and - ``"\u0327\u0043"`` compare differently, even though they both represent the - same unicode character (LATIN CAPITAL LETTER C WITH CEDILLA). To compare - strings in a human recognizable way, compare using - :func:`unicodedata.normalize`. +.. [#] The Unicode standard distinguishes between :dfn:`code points` + (e.g. U+0041) and :dfn:`abstract characters` (e.g. "LATIN CAPITAL LETTER A"). + While most abstract characters in Unicode are only represented using one + code point, there is a number of abstract characters that can in addition be + represented using a sequence of more than one code point. For example, the + abstract character "LATIN CAPITAL LETTER C WITH CEDILLA" can be represented + as a single :dfn:`precomposed character` at code position U+00C7, or as a + sequence of a :dfn:`base character` at code position U+0043 (LATIN CAPITAL + LETTER C), followed by a :dfn:`combining character` at code position U+0327 + (COMBINING CEDILLA). + + The comparison operators on strings compare at the level of Unicode code + points. This may be counter-intuitive to humans. For example, + ``"\u00C7" == "\u0043\u0327"`` is ``False``, even though both strings + represent the same abstract character "LATIN CAPITAL LETTER C WITH CEDILLA". + + To compare strings at the level of abstract characters (that is, in a way + intuitive to humans), use :func:`unicodedata.normalize`. .. [#] Due to automatic garbage-collection, free lists, and the dynamic nature of descriptors, you may notice seemingly unusual behaviour in certain uses of diff -r a824c40e8fc0 -r d69c5520c617 Lib/test/test_compare.py --- a/Lib/test/test_compare.py Sat Feb 21 15:26:02 2015 -0800 +++ b/Lib/test/test_compare.py Mon Mar 02 19:02:13 2015 +0100 @@ -1,28 +1,41 @@ +""" +Test equality and order comparisons. +""" + import unittest +from fractions import Fraction +from decimal import Decimal + from test import support -class Empty: - def __repr__(self): - return '' -class Cmp: - def __init__(self,arg): - self.arg = arg +class ComparisonSimpleTest(unittest.TestCase): + """ + A testcase that verifies the behavior of equality and order comparisons for + some simple cases. + """ - def __repr__(self): - return '' % self.arg + class Empty: + def __repr__(self): + return '' - def __eq__(self, other): - return self.arg == other + class Cmp: + def __init__(self, arg): + self.arg = arg -class Anything: - def __eq__(self, other): - return True + def __repr__(self): + return '' % self.arg - def __ne__(self, other): - return False + def __eq__(self, other): + return self.arg == other -class ComparisonTest(unittest.TestCase): + class Anything: + def __eq__(self, other): + return True + + def __ne__(self, other): + return False + set1 = [2, 2.0, 2, 2+0j, Cmp(2.0)] set2 = [[1], (3,), None, Empty()] candidates = set1 + set2 @@ -39,16 +52,15 @@ # Ensure default comparison compares id() of args L = [] for i in range(10): - L.insert(len(L)//2, Empty()) + L.insert(len(L)//2, ComparisonSimpleTest.Empty()) for a in L: for b in L: - self.assertEqual(a == b, id(a) == id(b), - 'a=%r, b=%r' % (a, b)) + self.assertEqual(a == b, a is b, 'a=%r, b=%r' % (a, b)) def test_ne_defaults_to_not_eq(self): - a = Cmp(1) - b = Cmp(1) - c = Cmp(2) + a = ComparisonSimpleTest.Cmp(1) + b = ComparisonSimpleTest.Cmp(1) + c = ComparisonSimpleTest.Cmp(2) self.assertIs(a == b, True) self.assertIs(a != b, False) self.assertIs(a != c, True) @@ -114,15 +126,854 @@ def test_issue_1393(self): x = lambda: None - self.assertEqual(x, Anything()) - self.assertEqual(Anything(), x) + self.assertEqual(x, ComparisonSimpleTest.Anything()) + self.assertEqual(ComparisonSimpleTest.Anything(), x) y = object() - self.assertEqual(y, Anything()) - self.assertEqual(Anything(), y) + self.assertEqual(y, ComparisonSimpleTest.Anything()) + self.assertEqual(ComparisonSimpleTest.Anything(), y) + + +class ComparisonFullTest(unittest.TestCase): + """ + A testcase that verifies the behavior of equality and ordering + comparisons for built-in types and user-defined classes that implement + relevant combinations of rich comparison methods. + """ + + + class CompBase(object): + """ + Base class for classes with rich comparison methods. + """ + meth = () # names of comparison methods implemented here. See + # assert_comparisons(). + def __init__(self, x=None): + self.x = x + + + # Class without any rich comparison methods + + class CompNone(CompBase): + pass + + + # Classes with all combinations of value-based equality comparison methods + + class CompEq(CompBase): + meth = ("eq",) + def __eq__(self, other): + return self.x == other.x + + class CompNe(CompBase): + meth = ("ne",) + def __ne__(self, other): + return self.x != other.x + + class CompEqNe(CompBase): + meth = ("eq", "ne") + def __eq__(self, other): + return self.x == other.x + def __ne__(self, other): + return self.x != other.x + + + # Classes with all combinations of value-based less/greater-than order + # comparison methods + + class CompLt(CompBase): + meth = ("lt",) + def __lt__(self, other): + return self.x < other.x + + class CompGt(CompBase): + meth = ("gt",) + def __gt__(self, other): + return self.x > other.x + + class CompLtGt(CompBase): + meth = ("lt", "gt") + def __lt__(self, other): + return self.x < other.x + def __gt__(self, other): + return self.x > other.x + + + # Classes with all combinations of value-based less/greater-or-equal-than + # order comparison methods + + class CompLe(CompBase): + meth = ("le",) + def __le__(self, other): + return self.x <= other.x + + class CompGe(CompBase): + meth = ("ge",) + def __ge__(self, other): + return self.x >= other.x + + class CompLeGe(CompBase): + meth = ("le", "ge") + def __le__(self, other): + return self.x <= other.x + def __ge__(self, other): + return self.x >= other.x + + + # It should be sufficient to combine the comparison methods only within + # each group: + all_comp_classes = (CompNone, + CompEq, CompNe, CompEqNe, # equal group + CompLt, CompGt, CompLtGt, # less/greater-than group + CompLe, CompGe, CompLeGe) # less/greater-or-equal group + + + def is_value_comparable(self, i1, i2, comp_kind): + """ + Return a boolean indicating whether the two input instances can be + compared based on their values (comparison based on identities does not + count). + True: The instances can be compared. + False: The instances cannot be compared. + + This is determined based on the type of the two instances. It takes + into account knowledge about the behavior of built-in types. Comparison + methods implemented in user-defined classes are not taken into account. + + Instances of built-in types that are not order-comparable (e.g. that + have default order comparison), or instances of built-in types that + will be equality-compared based on their identities (e.g. that have + default equality comparison), or instances of user-defined classes (for + which it is not known whether they implement comparison methods) will + be returned as False. + + i1, i2: The instances in question. + + comp_kind: Enumeration that indicates the kind of comparison: + "equal": Equality (==, !=) + "order": Ordering (<, <=, >=, >) + """ + + # Numbers are comparable across types. + # Except for complex, which is not order-comparable. + number_types = (int, float, complex, Fraction, Decimal) + if isinstance(i1, number_types) and isinstance(i2, number_types): + if comp_kind == "order" and \ + (isinstance(i1, complex) or isinstance(i2, complex)): + return False + else: + return True + + # Sets are comparable across their types. + # Sets are not totally ordered, but the order comparison operations + # are supported (they test for the subset/superset relationship). + set_types = (set, frozenset) + if isinstance(i1, set_types) and isinstance(i2, set_types): + return True + + # Byte sequences are comparable across their types. + bseq_types = (bytes, bytearray) + if isinstance(i1, bseq_types) and isinstance(i2, bseq_types): + return True + + # Other built-in collections are comparable only within the same type + # (i.e. both instances are of same type, including subtypes). + # Except for range and dict, which are not orderable. + for t in (str, tuple, list, range, dict): + isa1 = isinstance(i1, t) + isa2 = isinstance(i2, t) + if isa1 and isa2: + if comp_kind == "order" and t in (range, dict): + return False + else: + return True + if isa1 or isa2: + return False + + # For all other combinations of types, return False (see description) + return False + + + def create_sorted_insts(self, class_, values): + """ + Create a number of objects of type `class_` and return them in a list. + + `values` is a list of values that determines the value of data + attribute `x` of each object. + + The main feature of this function is that the objects in the result + list are sorted by their identity, and afterwards the values of the + `values` list are assigned to these objects. Testcases can utilize this + to assign decreasing values to objects with increasing identities, + which in turn allows asserting that order comparison is performed by + value and not by identity. + """ + + # create a list of instances with the default constructor + insts = [] + for i in range(0, len(values)): + insts.append(class_()) + + # sort the instance list by identity + insts.sort(key=id) + + # assign the provided values to the instances + i = 0 + for inst in insts: + inst.x = values[i] + i += 1 + + return insts + + + def assert_comparisons(self, i1, i2, equal, comp, i1_meth=None, + i2_meth=None): + """ + Perform assertions on equality and ordering comparison of two + instances. + + This function implements the knowledge about how equality and ordering + comparisons are supposed to work. + + i1, i2: Instances to be tested (of same or different type). + + equal: Boolean indicating the expected equality comparison result: + True means: i1 == i2 + False means: i1 != i2 + + comp: Integer indicating the expected order comparison result: + <0 means: i1 < i2 + 0 means: i1 == i2 + >0 means: i1 > i2 + None means: Undefined result + + Note that the expected results shown above just indicate + which order comparison expression evaluates to True; they + do not make any statement about whether the ordering is a + total ordering. + + i1_meth, i2_meth: Tuple of rich comparison method names (without + leading and trailing underscores) that are expected to be + available for the corresponding instance. This information + is only needed for instances of user-defined classes; the + knowledge about comparison methods for built-in types is + covered in is_value_comparable(). + Possible values for the tuple items are: + "eq", "ne", "lt", "le", "gt", "ge". + None means the same as an empty tuple. + """ + + if i1_meth is None: + i1_meth = () + if i2_meth is None: + i2_meth = () + + args_equal = dict(i1=i1, i2=i2, equal=equal, i1_meth=i1_meth, + i2_meth=i2_meth) + with self.subTest(**args_equal): + self.assert_eq_comparison_subtest(**args_equal) + with self.subTest(**args_equal): + self.assert_ne_comparison_subtest(**args_equal) + + args_comp = dict(i1=i1, i2=i2, comp=comp, i1_meth=i1_meth, + i2_meth=i2_meth) + with self.subTest(**args_comp): + self.assert_lt_comparison_subtest(**args_comp) + with self.subTest(**args_comp): + self.assert_le_comparison_subtest(**args_comp) + with self.subTest(**args_comp): + self.assert_gt_comparison_subtest(**args_comp) + with self.subTest(**args_comp): + self.assert_ge_comparison_subtest(**args_comp) + + def assert_eq_comparison_subtest(self, *, i1, i2, equal, i1_meth, i2_meth): + """ Test "==" comparison. + The comparison is performed in both directions of the operands. + """ + + self.assertIsNotNone(equal, + "Testcase error: Unexpected value for equal: None") + + if "eq" in i1_meth \ + or "eq" in i2_meth \ + or self.is_value_comparable(i1, i2, "equal"): + # There are value-based comparison methods; + # we expect what the testcase defined + self.assertEqual(i1 == i2, equal) + self.assertEqual(i2 == i1, equal) + else: + # There are no value-based comparison methods; + # we expect the default behavior of object + self.assertEqual(i1 == i2, i1 is i2) + self.assertEqual(i2 == i1, i2 is i1) + + def assert_ne_comparison_subtest(self, *, i1, i2, equal, i1_meth, i2_meth): + """ Test "!=" comparison. + The comparison is performed in both directions of the operands. + """ + + self.assertIsNotNone(equal, + "Testcase error: Unexpected value for equal: None") + + if not {"ne", "eq"}.isdisjoint(i1_meth + i2_meth) \ + or self.is_value_comparable(i1, i2, "equal"): + # There are value-based comparison methods; + # we expect what the testcase defined + self.assertEqual(i1 != i2, not equal) + self.assertEqual(i2 != i1, not equal) + else: + # There are no value-based comparison methods; + # we expect the default behavior of object + self.assertEqual(i1 != i2, i1 is not i2) + self.assertEqual(i2 != i1, i1 is not i2) + + def assert_lt_comparison_subtest(self, *, i1, i2, comp, i1_meth, i2_meth): + """ Test "<" comparison. + The comparison is performed in both directions of the operands. + """ + + if "lt" in i1_meth \ + or "gt" in i2_meth \ + or self.is_value_comparable(i1, i2, "order"): + self.assertIsNotNone(comp, + "Testcase error: Unexpected value for comp: None") + # There are value-based comparison methods; + # we expect what the testcase defined + self.assertEqual(i1 < i2, comp < 0) + self.assertEqual(i2 > i1, comp < 0) + else: + # There are no value-based comparison methods; + # we expect the default behavior of object + with self.assertRaises(TypeError): + i1 < i2 + with self.assertRaises(TypeError): + i2 > i1 + + def assert_le_comparison_subtest(self, *, i1, i2, comp, i1_meth, i2_meth): + """ Test "<=" comparison. + The comparison is performed in both directions of the operands. + """ + + if "le" in i1_meth \ + or "ge" in i2_meth \ + or self.is_value_comparable(i1, i2, "order"): + self.assertIsNotNone(comp, + "Testcase error: Unexpected value for comp: None") + # There are value-based comparison methods; + # we expect what the testcase defined + self.assertEqual(i1 <= i2, comp <= 0) + self.assertEqual(i2 >= i1, comp <= 0) + else: + # There are no value-based comparison methods; + # we expect the default behavior of object + with self.assertRaises(TypeError): + i1 <= i2 + with self.assertRaises(TypeError): + i2 >= i1 + + def assert_gt_comparison_subtest(self, *, i1, i2, comp, i1_meth, i2_meth): + """ Test ">" comparison. + The comparison is performed in both directions of the operands. + """ + + if "gt" in i1_meth \ + or "lt" in i2_meth \ + or self.is_value_comparable(i1, i2, "order"): + self.assertIsNotNone(comp, + "Testcase error: Unexpected value for comp: None") + # There are value-based comparison methods; + # we expect what the testcase defined + self.assertEqual(i1 > i2, comp > 0) + self.assertEqual(i2 < i1, comp > 0) + else: + # There are no value-based comparison methods; + # we expect the default behavior of object + with self.assertRaises(TypeError): + i1 > i2 + with self.assertRaises(TypeError): + i2 < i1 + + def assert_ge_comparison_subtest(self, *, i1, i2, comp, i1_meth, i2_meth): + """ Test ">=" comparison. + The comparison is performed in both directions of the operands. + """ + + if "ge" in i1_meth \ + or "le" in i2_meth \ + or self.is_value_comparable(i1, i2, "order"): + self.assertIsNotNone(comp, + "Testcase error: Unexpected value for comp: None") + # There are value-based comparison methods; + # we expect what the testcase defined + self.assertEqual(i1 >= i2, comp >= 0) + self.assertEqual(i2 <= i1, comp >= 0) + else: + # There are no value-based comparison methods; + # we expect the default behavior of object + with self.assertRaises(TypeError): + i1 >= i2 + with self.assertRaises(TypeError): + i2 <= i1 + + + def test_objects(self): + """ + Test comparison for two instances of type 'object'. + """ + + i1 = object() + i2 = object() + + self.assert_comparisons(i1, i1, True, None) + self.assert_comparisons(i1, i2, False, None) + + + def test_comp_classes(self): + """ + Test comparison for two instances of a number of classes derived from + object, that have different combinations of comparison methods + implemented. + + This test function tests all combinations of those classes, so that + instances are sometimes of different classes and sometimes of the same + class. + """ + + # Comparisons of objects of the same class. + + for cls in ComparisonFullTest.all_comp_classes: + + insts = self.create_sorted_insts(cls, (1, 2, 1)) + + # same object + self.assert_comparisons(insts[0], insts[0], True, 0, + cls.meth, cls.meth) + + # different objects, same value + self.assert_comparisons(insts[0], insts[2], True, 0, + cls.meth, cls.meth) + + # different objects, value ascending for ascending identities + self.assert_comparisons(insts[0], insts[1], False, -1, + cls.meth, cls.meth) + + # different objects, value descending for ascending identities. + # This is the interesting case to assert that order comparison + # is performed based on the value and not based on the identity. + self.assert_comparisons(insts[1], insts[2], False, +1, + cls.meth, cls.meth) + + # Comparisons of objects of the combination of all classes. + + for cls_a in ComparisonFullTest.all_comp_classes: + + for cls_b in ComparisonFullTest.all_comp_classes: + + insts_a = self.create_sorted_insts(cls_a, (1, 2)) + insts_b = self.create_sorted_insts(cls_b, (1, 2)) + + # Because we are comparing always across the lists, and the + # object identities are ascending only within each list, it + # cannot be predicted whether the values of the compared + # objects are ascending or descending for ascending identities. + # So basically, the create_sorted_insts() function is used + # only as a convenience, but its sorting behavior is not + # exploited in this testcase. + + # different objects, same value + self.assert_comparisons(insts_a[0], insts_b[0], True, 0, + cls_a.meth, cls_b.meth) + + # different objects, ascending or descending value for + # ascending identities + self.assert_comparisons(insts_a[0], insts_b[1], False, -1, + cls_a.meth, cls_b.meth) + + + def test_str_subclass(self): + """ + Test comparison for type ``str`` and its subclass ``StrSubclass``. + """ + + str_meth = () # str is a built-in type. Note, we only record + # user-defined comparison methods, not those provided by + # built-in types. + + class StrSubclass(str): + + meth = str_meth # inherits all of them from str, no additional + # user-defined comparison methods. + + c1 = StrSubclass("a") + c2 = StrSubclass("b") + c3 = StrSubclass("b") # different instance than c2 + self.assertTrue(c2 is not c3, "Testcase error: c2 is c3") + + s1 = str("a") + s2 = str("b") + s3 = str("b") # same instance as s2 + self.assertTrue(s2 is s3, "Testcase error: s2 is not s3") + + self.assert_comparisons(c1, c1, True, 0, StrSubclass.meth, + StrSubclass.meth) + self.assert_comparisons(c1, c2, False, -1, StrSubclass.meth, + StrSubclass.meth) + self.assert_comparisons(c2, c3, True, 0, StrSubclass.meth, + StrSubclass.meth) + + self.assert_comparisons(s1, s1, True, 0, str_meth, str_meth) + self.assert_comparisons(s1, s2, False, -1, str_meth, str_meth) + self.assert_comparisons(s2, s3, True, 0, str_meth, str_meth) + + self.assert_comparisons(c1, s2, False, -1, StrSubclass.meth, str_meth) + self.assert_comparisons(c2, s3, True, 0, StrSubclass.meth, str_meth) + + self.assert_comparisons(s1, c2, False, -1, str_meth, StrSubclass.meth) + self.assert_comparisons(s2, c3, True, 0, str_meth, StrSubclass.meth) + + + def test_numbers(self): + """ + Test comparison for number types. + """ + + num_meth = () # all number types are built-in types + + i1 = int(10001) + i2 = int(10002) + i3 = i1 + 1 # same value, different instance than i2 + i4 = i2 - 1 # same value, different instance than i1 + i5 = 42 + self.assertTrue(i2 is not i3, "Testcase error: i2 is i3") + self.assertTrue(i1 is not i4, "Testcase error: i1 is i4") + + f1 = 1.1 + f2 = 2.1 + f3 = f1 + 1 # same value, different instance than f2 + f4 = f2 - 1 # same value, different instance than f1 + f5 = 42.0 + self.assertTrue(f2 is not f3, "Testcase error: f2 is f3") + self.assertTrue(f1 is not f4, "Testcase error: f1 is f4") + + c1 = 1+1j + c2 = 2+2j + c3 = 2+2j # same value, different instance than c2 + c4 = 1+1j # same value, different instance than c1 + c5 = 42+0j + self.assertTrue(c2 is not c3, "Testcase error: c2 is c3") + self.assertTrue(c1 is not c4, "Testcase error: c1 is c4") + + q1 = Fraction(1,2) + q2 = Fraction(2,3) + q3 = Fraction(2,3) # same value, different instance than q2 + q4 = Fraction(1,2) # same value, different instance than q1 + q5 = Fraction(84,2) + self.assertTrue(q2 is not q3, "Testcase error: q2 is q3") + self.assertTrue(q1 is not q4, "Testcase error: q1 is q4") + + d1 = Decimal('1.2') + d2 = Decimal('2.3') + d3 = Decimal('2.3') # same value, different instance than d2 + d4 = Decimal('1.2') # same value, different instance than d1 + d5 = Decimal('42.0') + self.assertTrue(d2 is not d3, "Testcase error: d2 is d3") + self.assertTrue(d1 is not d4, "Testcase error: d1 is d4") + + # Same types + + self.assert_comparisons(i1, i1, True, 0, num_meth, num_meth) + self.assert_comparisons(i1, i2, False, -1, num_meth, num_meth) + self.assert_comparisons(i2, i3, True, 0, num_meth, num_meth) + self.assert_comparisons(i3, i4, False, +1, num_meth, num_meth) + + self.assert_comparisons(f1, f1, True, 0, num_meth, num_meth) + self.assert_comparisons(f1, f2, False, -1, num_meth, num_meth) + self.assert_comparisons(f2, f3, True, 0, num_meth, num_meth) + self.assert_comparisons(f3, f4, False, +1, num_meth, num_meth) + + self.assert_comparisons(c1, c1, True, None, num_meth, num_meth) + self.assert_comparisons(c1, c2, False, None, num_meth, num_meth) + self.assert_comparisons(c2, c3, True, None, num_meth, num_meth) + self.assert_comparisons(c3, c4, False, None, num_meth, num_meth) + + self.assert_comparisons(q1, q1, True, 0, num_meth, num_meth) + self.assert_comparisons(q1, q2, False, -1, num_meth, num_meth) + self.assert_comparisons(q2, q3, True, 0, num_meth, num_meth) + self.assert_comparisons(q3, q4, False, +1, num_meth, num_meth) + + self.assert_comparisons(d1, d1, True, 0, num_meth, num_meth) + self.assert_comparisons(d1, d2, False, -1, num_meth, num_meth) + self.assert_comparisons(d2, d3, True, 0, num_meth, num_meth) + self.assert_comparisons(d3, d4, False, +1, num_meth, num_meth) + + # Mixing types + + self.assert_comparisons(i5, f5, True, 0, num_meth, num_meth) + self.assert_comparisons(i5, c5, True, None, num_meth, num_meth) + self.assert_comparisons(i5, q5, True, 0, num_meth, num_meth) + self.assert_comparisons(i5, d5, True, 0, num_meth, num_meth) + + self.assert_comparisons(f5, c5, True, None, num_meth, num_meth) + self.assert_comparisons(f5, q5, True, 0, num_meth, num_meth) + self.assert_comparisons(f5, d5, True, 0, num_meth, num_meth) + + self.assert_comparisons(c5, q5, True, None, num_meth, num_meth) + self.assert_comparisons(c5, d5, True, None, num_meth, num_meth) + + self.assert_comparisons(q5, d5, True, 0, num_meth, num_meth) + + self.assert_comparisons(i1, f1, False, +1, num_meth, num_meth) + self.assert_comparisons(i1, c1, False, None, num_meth, num_meth) + self.assert_comparisons(i1, q1, False, +1, num_meth, num_meth) + self.assert_comparisons(i1, d1, False, +1, num_meth, num_meth) + + self.assert_comparisons(f1, c1, False, None, num_meth, num_meth) + self.assert_comparisons(f1, q1, False, +1, num_meth, num_meth) + self.assert_comparisons(f1, d1, False, -1, num_meth, num_meth) + + self.assert_comparisons(c1, q1, False, None, num_meth, num_meth) + self.assert_comparisons(c1, d1, False, None, num_meth, num_meth) + + self.assert_comparisons(q1, d1, False, -1, num_meth, num_meth) + + + def test_sequences(self): + """ + Test comparison for sequences (list, tuple, range). + """ + + seq_meth = () # these sequences are built-in types + + l1 = [1,2] + l2 = [2,3] + l3 = [2,3] # same value, different instance than l2 + l4 = [1,2] # same value, different instance than l1 + self.assertTrue(l2 is not l3, "Testcase error: l2 is l3") + self.assertTrue(l1 is not l4, "Testcase error: l1 is l4") + + t1 = (1,2) + t2 = (2,3) + t3 = (2,3) # same value, different instance than t2 + t4 = (1,2) # same value, different instance than t1 + self.assertTrue(t2 is not t3, "Testcase error: t2 is t3") + self.assertTrue(t1 is not t4, "Testcase error: t1 is t4") + + r1 = range(1,2) + r2 = range(2,2) + r3 = range(2,2) # same value, different instance than r2 + r4 = range(1,2) # same value, different instance than r1 + self.assertTrue(r2 is not r3, "Testcase error: r2 is r3") + self.assertTrue(r1 is not r4, "Testcase error: r1 is r4") + + # Same types + + self.assert_comparisons(t1, t1, True, 0, seq_meth, seq_meth) + self.assert_comparisons(t1, t2, False, -1, seq_meth, seq_meth) + self.assert_comparisons(t2, t3, True, 0, seq_meth, seq_meth) + self.assert_comparisons(t3, t4, False, +1, seq_meth, seq_meth) + + self.assert_comparisons(l1, l1, True, 0, seq_meth, seq_meth) + self.assert_comparisons(l1, l2, False, -1, seq_meth, seq_meth) + self.assert_comparisons(l2, l3, True, 0, seq_meth, seq_meth) + self.assert_comparisons(l3, l4, False, +1, seq_meth, seq_meth) + + self.assert_comparisons(r1, r1, True, None, seq_meth, seq_meth) + self.assert_comparisons(r1, r2, False, None, seq_meth, seq_meth) + self.assert_comparisons(r2, r3, True, None, seq_meth, seq_meth) + self.assert_comparisons(r3, r4, False, None, seq_meth, seq_meth) + + # Mixing types + + self.assert_comparisons(t1, l1, False, None, seq_meth, seq_meth) + + self.assert_comparisons(l1, r1, False, None, seq_meth, seq_meth) + + self.assert_comparisons(r1, t1, False, None, seq_meth, seq_meth) + + + def test_binary_sequences(self): + """ + Test comparison for binary sequences (bytes, bytearray). + """ + + bseq_meth = () # these are built-in types + + bs1 = b'a1' + bs2 = b'b2' + bs3 = b'b' + b'2' # same value, different instance than bs2 + bs4 = b'a' + b'1' # same value, different instance than bs1 + self.assertTrue(bs2 is not bs3, "Testcase error: bs2 is bs3") + self.assertTrue(bs1 is not bs4, "Testcase error: bs1 is bs4") + + ba1 = bytearray(b'a1') + ba2 = bytearray(b'b2') + ba3 = bytearray(b'b2') # same value, different instance than ba2 + ba4 = bytearray(b'a1') # same value, different instance than ba1 + self.assertTrue(ba2 is not ba3, "Testcase error: ba2 is ba3") + self.assertTrue(ba1 is not ba4, "Testcase error: ba1 is ba4") + + # Same types + + self.assert_comparisons(bs1, bs1, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(bs1, bs2, False, -1, bseq_meth, bseq_meth) + self.assert_comparisons(bs2, bs3, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(bs3, bs4, False, +1, bseq_meth, bseq_meth) + + self.assert_comparisons(ba1, ba1, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(ba1, ba2, False, -1, bseq_meth, bseq_meth) + self.assert_comparisons(ba2, ba3, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(ba3, ba4, False, +1, bseq_meth, bseq_meth) + + # Mixing types + + self.assert_comparisons(bs1, ba1, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(bs1, ba2, False, -1, bseq_meth, bseq_meth) + self.assert_comparisons(bs2, ba3, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(bs3, ba4, False, +1, bseq_meth, bseq_meth) + + self.assert_comparisons(ba1, bs1, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(ba1, bs2, False, -1, bseq_meth, bseq_meth) + self.assert_comparisons(ba2, bs3, True, 0, bseq_meth, bseq_meth) + self.assert_comparisons(ba3, bs4, False, +1, bseq_meth, bseq_meth) + + + def test_sets(self): + """ + Test comparison for sets (set, frozenset). + """ + + set_meth = () # these sets are built-in types + + s1 = {1,2} + s2 = {1,2,3} # for sets, <, <=, >=, > are subset-of relations + s3 = {1,2,3} # same value, different instance than s2 + s4 = {1,2} # same value, different instance than s1 + self.assertTrue(s2 is not s3, "Testcase error: s2 is s3") + self.assertTrue(s1 is not s4, "Testcase error: s1 is s4") + + f1 = frozenset({1,2}) + f2 = frozenset({1,2,3}) + f3 = frozenset({1,2,3}) # same value, different instance than f2 + f4 = frozenset({1,2}) # same value, different instance than f1 + self.assertTrue(f2 is not f3, "Testcase error: f2 is f3") + self.assertTrue(f1 is not f4, "Testcase error: f1 is f4") + + # Same types + + self.assert_comparisons(s1, s1, True, 0, set_meth, set_meth) + self.assert_comparisons(s1, s2, False, -1, set_meth, set_meth) + self.assert_comparisons(s2, s3, True, 0, set_meth, set_meth) + self.assert_comparisons(s3, s4, False, +1, set_meth, set_meth) + + self.assert_comparisons(f1, f1, True, 0, set_meth, set_meth) + self.assert_comparisons(f1, f2, False, -1, set_meth, set_meth) + self.assert_comparisons(f2, f3, True, 0, set_meth, set_meth) + self.assert_comparisons(f3, f4, False, +1, set_meth, set_meth) + + # Mixing types + + self.assert_comparisons(s1, f1, True, 0, set_meth, set_meth) + self.assert_comparisons(s1, f2, False, -1, set_meth, set_meth) + self.assert_comparisons(s2, f3, True, 0, set_meth, set_meth) + self.assert_comparisons(s3, f4, False, +1, set_meth, set_meth) + + self.assert_comparisons(f1, s1, True, 0, set_meth, set_meth) + self.assert_comparisons(f1, s2, False, -1, set_meth, set_meth) + self.assert_comparisons(f2, s3, True, 0, set_meth, set_meth) + self.assert_comparisons(f3, s4, False, +1, set_meth, set_meth) + + + def test_mappings(self): + """ + Test comparison for mappings (dict). + """ + + map_meth = () # these mappings are built-in types + + d1 = {1:"a",2:"b"} + d2 = {2:"b",3:"c"} + d3 = {3:"c",2:"b"} # same value!, different instance than d2 + d4 = {1:"a",2:"b"} # same value, different instance than d1 + self.assertTrue(d2 is not d3, "Testcase error: d2 is d3") + self.assertTrue(d1 is not d4, "Testcase error: d1 is d4") + + self.assert_comparisons(d1, d1, True, None, map_meth, map_meth) + self.assert_comparisons(d1, d2, False, None, map_meth, map_meth) + self.assert_comparisons(d2, d3, True, None, map_meth, map_meth) + self.assert_comparisons(d3, d4, False, None, map_meth, map_meth) + + + def test__is_value_comparable(self): + """ + Internal test for is_value_comparable(). + + The extra underscore ensures that this test is executed before + the others that use that function. + """ + + tests = ( + # tuple( inst1, inst2, comp_kind, exp_result ) + + # Numbers + (1, 1.0, "equal", True), + (1.0, 1+1j, "equal", True), + (1.0, 1+1j, "order", False), + (1+1j, Fraction(2,3), "equal", True), + (1+1j, Decimal('1234.56'), "equal", True), + # with others + (1, bytes(b"b"), "equal", False), + + # String and binary sequences (bytes, bytearray) + (str("a"), str("b"), "equal", True), + (bytes(b"a"), bytes(b"b"), "equal", True), + (bytearray(b"a"), bytearray(b"b"), "equal", True), + # with others + (str("a"), bytes(b"b"), "equal", False), + (str("a"), bytearray(b"b"), "equal", False), + (bytes(b"a"), bytearray(b"b"), "equal", True), + + # Sequences (list, tuple, range) + ([1,2], [2,3], "equal", True), + ((1,2), (2,3), "equal", True), + (range(1,2), range(2,2), "equal", True), + (range(1,2), range(2,2), "order", False), + # with others + ([1,2], (2,3), "equal", False), + ((1,2), range(2,2), "equal", False), + ((1,2), range(2,2), "order", False), + ([1,2], range(2,2), "equal", False), + ([1,2], range(2,2), "order", False), + + # Sets (set, frozenset) + ({1,2}, {2,3}, "equal", True), + ({1,2}, {2,3}, "order", True), + (frozenset({1,2}), frozenset({2,3}), "equal", True), + (frozenset({1,2}), frozenset({2,3}), "order", True), + ({1,2}, frozenset({2,3}), "equal", True), + ({1,2}, frozenset({2,3}), "order", True), + (frozenset({1,2}), {2,3}, "equal", True), + (frozenset({1,2}), {2,3}, "order", True), + # with others + ({1,2}, [2,3], "equal", False), + ({1,2}, (2,3), "order", False), + + # Mappings (dicts) + ({1:"a",2:"b"}, {2:"b",3:"c"}, "equal", True), + ({1:"a",2:"b"}, {2:"b",3:"c"}, "order", False), + # with others + ({1:"a",2:"b"}, {2,3}, "equal", False), + ) + + for inst1, inst2, comp_kind, exp_result in tests: + act_result = self.is_value_comparable(inst1, inst2, comp_kind) + self.assertEqual(act_result, exp_result, + "inst1=%r, inst2=%r, comp_kind=%s, " \ + "exp_result=%s, act_result=%s" % \ + (inst1, inst2, comp_kind, exp_result, act_result)) def test_main(): - support.run_unittest(ComparisonTest) + support.run_unittest(ComparisonSimpleTest) + support.run_unittest(ComparisonFullTest) if __name__ == '__main__': test_main()