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Diffstat (limited to 'bitbake/lib/bb/namedtuple_with_abc.py')
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diff --git a/bitbake/lib/bb/namedtuple_with_abc.py b/bitbake/lib/bb/namedtuple_with_abc.py new file mode 100644 index 0000000000..f5e0a3f3d5 --- /dev/null +++ b/bitbake/lib/bb/namedtuple_with_abc.py | |||
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| 1 | # http://code.activestate.com/recipes/577629-namedtupleabc-abstract-base-class-mix-in-for-named/ | ||
| 2 | #!/usr/bin/env python | ||
| 3 | # Copyright (c) 2011 Jan Kaliszewski (zuo). Available under the MIT License. | ||
| 4 | |||
| 5 | """ | ||
| 6 | namedtuple_with_abc.py: | ||
| 7 | * named tuple mix-in + ABC (abstract base class) recipe, | ||
| 8 | * works under Python 2.6, 2.7 as well as 3.x. | ||
| 9 | |||
| 10 | Import this module to patch collections.namedtuple() factory function | ||
| 11 | -- enriching it with the 'abc' attribute (an abstract base class + mix-in | ||
| 12 | for named tuples) and decorating it with a wrapper that registers each | ||
| 13 | newly created named tuple as a subclass of namedtuple.abc. | ||
| 14 | |||
| 15 | How to import: | ||
| 16 | import collections, namedtuple_with_abc | ||
| 17 | or: | ||
| 18 | import namedtuple_with_abc | ||
| 19 | from collections import namedtuple | ||
| 20 | # ^ in this variant you must import namedtuple function | ||
| 21 | # *after* importing namedtuple_with_abc module | ||
| 22 | or simply: | ||
| 23 | from namedtuple_with_abc import namedtuple | ||
| 24 | |||
| 25 | Simple usage example: | ||
| 26 | class Credentials(namedtuple.abc): | ||
| 27 | _fields = 'username password' | ||
| 28 | def __str__(self): | ||
| 29 | return ('{0.__class__.__name__}' | ||
| 30 | '(username={0.username}, password=...)'.format(self)) | ||
| 31 | print(Credentials("alice", "Alice's password")) | ||
| 32 | |||
| 33 | For more advanced examples -- see below the "if __name__ == '__main__':". | ||
| 34 | """ | ||
| 35 | |||
| 36 | import collections | ||
| 37 | from abc import ABCMeta, abstractproperty | ||
| 38 | from functools import wraps | ||
| 39 | from sys import version_info | ||
| 40 | |||
| 41 | __all__ = ('namedtuple',) | ||
| 42 | _namedtuple = collections.namedtuple | ||
| 43 | |||
| 44 | |||
| 45 | class _NamedTupleABCMeta(ABCMeta): | ||
| 46 | '''The metaclass for the abstract base class + mix-in for named tuples.''' | ||
| 47 | def __new__(mcls, name, bases, namespace): | ||
| 48 | fields = namespace.get('_fields') | ||
| 49 | for base in bases: | ||
| 50 | if fields is not None: | ||
| 51 | break | ||
| 52 | fields = getattr(base, '_fields', None) | ||
| 53 | if not isinstance(fields, abstractproperty): | ||
| 54 | basetuple = _namedtuple(name, fields) | ||
| 55 | bases = (basetuple,) + bases | ||
| 56 | namespace.pop('_fields', None) | ||
| 57 | namespace.setdefault('__doc__', basetuple.__doc__) | ||
| 58 | namespace.setdefault('__slots__', ()) | ||
| 59 | return ABCMeta.__new__(mcls, name, bases, namespace) | ||
| 60 | |||
| 61 | |||
| 62 | exec( | ||
| 63 | # Python 2.x metaclass declaration syntax | ||
| 64 | """class _NamedTupleABC(object): | ||
| 65 | '''The abstract base class + mix-in for named tuples.''' | ||
| 66 | __metaclass__ = _NamedTupleABCMeta | ||
| 67 | _fields = abstractproperty()""" if version_info[0] < 3 else | ||
| 68 | # Python 3.x metaclass declaration syntax | ||
| 69 | """class _NamedTupleABC(metaclass=_NamedTupleABCMeta): | ||
| 70 | '''The abstract base class + mix-in for named tuples.''' | ||
| 71 | _fields = abstractproperty()""" | ||
| 72 | ) | ||
| 73 | |||
| 74 | |||
| 75 | _namedtuple.abc = _NamedTupleABC | ||
| 76 | #_NamedTupleABC.register(type(version_info)) # (and similar, in the future...) | ||
| 77 | |||
| 78 | @wraps(_namedtuple) | ||
| 79 | def namedtuple(*args, **kwargs): | ||
| 80 | '''Named tuple factory with namedtuple.abc subclass registration.''' | ||
| 81 | cls = _namedtuple(*args, **kwargs) | ||
| 82 | _NamedTupleABC.register(cls) | ||
| 83 | return cls | ||
| 84 | |||
| 85 | collections.namedtuple = namedtuple | ||
| 86 | |||
| 87 | |||
| 88 | |||
| 89 | |||
| 90 | if __name__ == '__main__': | ||
| 91 | |||
| 92 | '''Examples and explanations''' | ||
| 93 | |||
| 94 | # Simple usage | ||
| 95 | |||
| 96 | class MyRecord(namedtuple.abc): | ||
| 97 | _fields = 'x y z' # such form will be transformed into ('x', 'y', 'z') | ||
| 98 | def _my_custom_method(self): | ||
| 99 | return list(self._asdict().items()) | ||
| 100 | # (the '_fields' attribute belongs to the named tuple public API anyway) | ||
| 101 | |||
| 102 | rec = MyRecord(1, 2, 3) | ||
| 103 | print(rec) | ||
| 104 | print(rec._my_custom_method()) | ||
| 105 | print(rec._replace(y=222)) | ||
| 106 | print(rec._replace(y=222)._my_custom_method()) | ||
| 107 | |||
| 108 | # Custom abstract classes... | ||
| 109 | |||
| 110 | class MyAbstractRecord(namedtuple.abc): | ||
| 111 | def _my_custom_method(self): | ||
| 112 | return list(self._asdict().items()) | ||
| 113 | |||
| 114 | try: | ||
| 115 | MyAbstractRecord() # (abstract classes cannot be instantiated) | ||
| 116 | except TypeError as exc: | ||
| 117 | print(exc) | ||
| 118 | |||
| 119 | class AnotherAbstractRecord(MyAbstractRecord): | ||
| 120 | def __str__(self): | ||
| 121 | return '<<<{0}>>>'.format(super(AnotherAbstractRecord, | ||
| 122 | self).__str__()) | ||
| 123 | |||
| 124 | # ...and their non-abstract subclasses | ||
| 125 | |||
| 126 | class MyRecord2(MyAbstractRecord): | ||
| 127 | _fields = 'a, b' | ||
| 128 | |||
| 129 | class MyRecord3(AnotherAbstractRecord): | ||
| 130 | _fields = 'p', 'q', 'r' | ||
| 131 | |||
| 132 | rec2 = MyRecord2('foo', 'bar') | ||
| 133 | print(rec2) | ||
| 134 | print(rec2._my_custom_method()) | ||
| 135 | print(rec2._replace(b=222)) | ||
| 136 | print(rec2._replace(b=222)._my_custom_method()) | ||
| 137 | |||
| 138 | rec3 = MyRecord3('foo', 'bar', 'baz') | ||
| 139 | print(rec3) | ||
| 140 | print(rec3._my_custom_method()) | ||
| 141 | print(rec3._replace(q=222)) | ||
| 142 | print(rec3._replace(q=222)._my_custom_method()) | ||
| 143 | |||
| 144 | # You can also subclass non-abstract ones... | ||
| 145 | |||
| 146 | class MyRecord33(MyRecord3): | ||
| 147 | def __str__(self): | ||
| 148 | return '< {0!r}, ..., {0!r} >'.format(self.p, self.r) | ||
| 149 | |||
| 150 | rec33 = MyRecord33('foo', 'bar', 'baz') | ||
| 151 | print(rec33) | ||
| 152 | print(rec33._my_custom_method()) | ||
| 153 | print(rec33._replace(q=222)) | ||
| 154 | print(rec33._replace(q=222)._my_custom_method()) | ||
| 155 | |||
| 156 | # ...and even override the magic '_fields' attribute again | ||
| 157 | |||
| 158 | class MyRecord345(MyRecord3): | ||
| 159 | _fields = 'e f g h i j k' | ||
| 160 | |||
| 161 | rec345 = MyRecord345(1, 2, 3, 4, 3, 2, 1) | ||
| 162 | print(rec345) | ||
| 163 | print(rec345._my_custom_method()) | ||
| 164 | print(rec345._replace(f=222)) | ||
| 165 | print(rec345._replace(f=222)._my_custom_method()) | ||
| 166 | |||
| 167 | # Mixing-in some other classes is also possible: | ||
| 168 | |||
| 169 | class MyMixIn(object): | ||
| 170 | def method(self): | ||
| 171 | return "MyMixIn.method() called" | ||
| 172 | def _my_custom_method(self): | ||
| 173 | return "MyMixIn._my_custom_method() called" | ||
| 174 | def count(self, item): | ||
| 175 | return "MyMixIn.count({0}) called".format(item) | ||
| 176 | def _asdict(self): # (cannot override a namedtuple method, see below) | ||
| 177 | return "MyMixIn._asdict() called" | ||
| 178 | |||
| 179 | class MyRecord4(MyRecord33, MyMixIn): # mix-in on the right | ||
| 180 | _fields = 'j k l x' | ||
| 181 | |||
| 182 | class MyRecord5(MyMixIn, MyRecord33): # mix-in on the left | ||
| 183 | _fields = 'j k l x y' | ||
| 184 | |||
| 185 | rec4 = MyRecord4(1, 2, 3, 2) | ||
| 186 | print(rec4) | ||
| 187 | print(rec4.method()) | ||
| 188 | print(rec4._my_custom_method()) # MyRecord33's | ||
| 189 | print(rec4.count(2)) # tuple's | ||
| 190 | print(rec4._replace(k=222)) | ||
| 191 | print(rec4._replace(k=222).method()) | ||
| 192 | print(rec4._replace(k=222)._my_custom_method()) # MyRecord33's | ||
| 193 | print(rec4._replace(k=222).count(8)) # tuple's | ||
| 194 | |||
| 195 | rec5 = MyRecord5(1, 2, 3, 2, 1) | ||
| 196 | print(rec5) | ||
| 197 | print(rec5.method()) | ||
| 198 | print(rec5._my_custom_method()) # MyMixIn's | ||
| 199 | print(rec5.count(2)) # MyMixIn's | ||
| 200 | print(rec5._replace(k=222)) | ||
| 201 | print(rec5._replace(k=222).method()) | ||
| 202 | print(rec5._replace(k=222)._my_custom_method()) # MyMixIn's | ||
| 203 | print(rec5._replace(k=222).count(2)) # MyMixIn's | ||
| 204 | |||
| 205 | # None that behavior: the standard namedtuple methods cannot be | ||
| 206 | # overriden by a foreign mix-in -- even if the mix-in is declared | ||
| 207 | # as the leftmost base class (but, obviously, you can override them | ||
| 208 | # in the defined class or its subclasses): | ||
| 209 | |||
| 210 | print(rec4._asdict()) # (returns a dict, not "MyMixIn._asdict() called") | ||
| 211 | print(rec5._asdict()) # (returns a dict, not "MyMixIn._asdict() called") | ||
| 212 | |||
| 213 | class MyRecord6(MyRecord33): | ||
| 214 | _fields = 'j k l x y z' | ||
| 215 | def _asdict(self): | ||
| 216 | return "MyRecord6._asdict() called" | ||
| 217 | rec6 = MyRecord6(1, 2, 3, 1, 2, 3) | ||
| 218 | print(rec6._asdict()) # (this returns "MyRecord6._asdict() called") | ||
| 219 | |||
| 220 | # All that record classes are real subclasses of namedtuple.abc: | ||
| 221 | |||
| 222 | assert issubclass(MyRecord, namedtuple.abc) | ||
| 223 | assert issubclass(MyAbstractRecord, namedtuple.abc) | ||
| 224 | assert issubclass(AnotherAbstractRecord, namedtuple.abc) | ||
| 225 | assert issubclass(MyRecord2, namedtuple.abc) | ||
| 226 | assert issubclass(MyRecord3, namedtuple.abc) | ||
| 227 | assert issubclass(MyRecord33, namedtuple.abc) | ||
| 228 | assert issubclass(MyRecord345, namedtuple.abc) | ||
| 229 | assert issubclass(MyRecord4, namedtuple.abc) | ||
| 230 | assert issubclass(MyRecord5, namedtuple.abc) | ||
| 231 | assert issubclass(MyRecord6, namedtuple.abc) | ||
| 232 | |||
| 233 | # ...but abstract ones are not subclasses of tuple | ||
| 234 | # (and this is what you probably want): | ||
| 235 | |||
| 236 | assert not issubclass(MyAbstractRecord, tuple) | ||
| 237 | assert not issubclass(AnotherAbstractRecord, tuple) | ||
| 238 | |||
| 239 | assert issubclass(MyRecord, tuple) | ||
| 240 | assert issubclass(MyRecord2, tuple) | ||
| 241 | assert issubclass(MyRecord3, tuple) | ||
| 242 | assert issubclass(MyRecord33, tuple) | ||
| 243 | assert issubclass(MyRecord345, tuple) | ||
| 244 | assert issubclass(MyRecord4, tuple) | ||
| 245 | assert issubclass(MyRecord5, tuple) | ||
| 246 | assert issubclass(MyRecord6, tuple) | ||
| 247 | |||
| 248 | # Named tuple classes created with namedtuple() factory function | ||
| 249 | # (in the "traditional" way) are registered as "virtual" subclasses | ||
| 250 | # of namedtuple.abc: | ||
| 251 | |||
| 252 | MyTuple = namedtuple('MyTuple', 'a b c') | ||
| 253 | mt = MyTuple(1, 2, 3) | ||
| 254 | assert issubclass(MyTuple, namedtuple.abc) | ||
| 255 | assert isinstance(mt, namedtuple.abc) | ||
