Question

a recent question中的讨论，min/max()需要对象进行比较，让我想知道如何找到哪些Python类型支持特定方法（__cmp__，或者{{1} } - 细节不重要。）

首先，似乎能够获得所有类型的列表。然后我可以简单地检查__lt__。那么我如何枚举所有数据类型？

Answer 1

>>> import __builtin__
>>> builtin_types= [t
...  for t in __builtin__.__dict__.itervalues()
...  if isinstance(t, type)]

>>> import pprint
>>> pprint.pprint(sorted(builtin_types, key=repr))
[<type 'basestring'>,
 <type 'bool'>,
 <type 'buffer'>,
 <type 'bytearray'>,
 <type 'classmethod'>,
 <type 'complex'>,
 <type 'dict'>,
 <type 'enumerate'>,
 <type 'exceptions.ArithmeticError'>,
 <type 'exceptions.AssertionError'>,
 <type 'exceptions.AttributeError'>,
 <type 'exceptions.BaseException'>,
 <type 'exceptions.BufferError'>,
 <type 'exceptions.BytesWarning'>,
 <type 'exceptions.DeprecationWarning'>,
 <type 'exceptions.EOFError'>,
 <type 'exceptions.EnvironmentError'>,
 <type 'exceptions.Exception'>,
 <type 'exceptions.FloatingPointError'>,
 <type 'exceptions.FutureWarning'>,
 <type 'exceptions.GeneratorExit'>,
 <type 'exceptions.IOError'>,
 <type 'exceptions.ImportError'>,
 <type 'exceptions.ImportWarning'>,
 <type 'exceptions.IndentationError'>,
 <type 'exceptions.IndexError'>,
 <type 'exceptions.KeyError'>,
 <type 'exceptions.KeyboardInterrupt'>,
 <type 'exceptions.LookupError'>,
 <type 'exceptions.MemoryError'>,
 <type 'exceptions.NameError'>,
 <type 'exceptions.NotImplementedError'>,
 <type 'exceptions.OSError'>,
 <type 'exceptions.OverflowError'>,
 <type 'exceptions.PendingDeprecationWarning'>,
 <type 'exceptions.ReferenceError'>,
 <type 'exceptions.RuntimeError'>,
 <type 'exceptions.RuntimeWarning'>,
 <type 'exceptions.StandardError'>,
 <type 'exceptions.StopIteration'>,
 <type 'exceptions.SyntaxError'>,
 <type 'exceptions.SyntaxWarning'>,
 <type 'exceptions.SystemError'>,
 <type 'exceptions.SystemExit'>,
 <type 'exceptions.TabError'>,
 <type 'exceptions.TypeError'>,
 <type 'exceptions.UnboundLocalError'>,
 <type 'exceptions.UnicodeDecodeError'>,
 <type 'exceptions.UnicodeEncodeError'>,
 <type 'exceptions.UnicodeError'>,
 <type 'exceptions.UnicodeTranslateError'>,
 <type 'exceptions.UnicodeWarning'>,
 <type 'exceptions.UserWarning'>,
 <type 'exceptions.ValueError'>,
 <type 'exceptions.Warning'>,
 <type 'exceptions.ZeroDivisionError'>,
 <type 'file'>,
 <type 'float'>,
 <type 'frozenset'>,
 <type 'int'>,
 <type 'list'>,
 <type 'long'>,
 <type 'object'>,
 <type 'property'>,
 <type 'reversed'>,
 <type 'set'>,
 <type 'slice'>,
 <type 'staticmethod'>,
 <type 'str'>,
 <type 'str'>,
 <type 'super'>,
 <type 'tuple'>,
 <type 'type'>,
 <type 'unicode'>,
 <type 'xrange'>]

Answer 2

relational special methods的存在不足以保证可比性;如果方法不喜欢传递给它们的特定类型，它们仍然可以引发异常。

Answer 3

@tzot答案不能使用python 3.x因为__builtin__模块更改了名称和结构。您现在应该使用builtin模块。

try :
    import __builtin__
except: 
    # Python 3.x
    import builtins

try : 
    builtin_types = [t for t in __builtin__.__dict__.itervalues() if isinstance(t, type)]
except:
    builtin_types = [getattr(builtins, d) for d in dir(builtins) if isinstance(getattr(builtins, d), type)]

现在使用Python 3.x：

>>> from pprint import pprint 
>>> pprint(builtin_types)
[<class 'ArithmeticError'>,
 <class 'AssertionError'>,
 <class 'AttributeError'>,
 <class 'BaseException'>,
 <class 'BlockingIOError'>,
 <class 'BrokenPipeError'>,
 <class 'BufferError'>,
 <class 'BytesWarning'>,
 <class 'ChildProcessError'>,
 <class 'ConnectionAbortedError'>,
 <class 'ConnectionError'>,
 <class 'ConnectionRefusedError'>,
 <class 'ConnectionResetError'>,
 <class 'DeprecationWarning'>,
 <class 'EOFError'>,
 <class 'OSError'>,
 <class 'Exception'>,
 <class 'FileExistsError'>,
 <class 'FileNotFoundError'>,
 <class 'FloatingPointError'>,
 <class 'FutureWarning'>,
 <class 'GeneratorExit'>,
 <class 'OSError'>,
 <class 'ImportError'>,
 <class 'ImportWarning'>,
 <class 'IndentationError'>,
 <class 'IndexError'>,
 <class 'InterruptedError'>,
 <class 'IsADirectoryError'>,
 <class 'KeyError'>,
 <class 'KeyboardInterrupt'>,
 <class 'LookupError'>,
 <class 'MemoryError'>,
 <class 'NameError'>,
 <class 'NotADirectoryError'>,
 <class 'NotImplementedError'>,
 <class 'OSError'>,
 <class 'OverflowError'>,
 <class 'PendingDeprecationWarning'>,
 <class 'PermissionError'>,
 <class 'ProcessLookupError'>,
 <class 'RecursionError'>,
 <class 'ReferenceError'>,
 <class 'ResourceWarning'>,
 <class 'RuntimeError'>,
 <class 'RuntimeWarning'>,
 <class 'StopAsyncIteration'>,
 <class 'StopIteration'>,
 <class 'SyntaxError'>,
 <class 'SyntaxWarning'>,
 <class 'SystemError'>,
 <class 'SystemExit'>,
 <class 'TabError'>,
 <class 'TimeoutError'>,
 <class 'TypeError'>,
 <class 'UnboundLocalError'>,
 <class 'UnicodeDecodeError'>,
 <class 'UnicodeEncodeError'>,
 <class 'UnicodeError'>,
 <class 'UnicodeTranslateError'>,
 <class 'UnicodeWarning'>,
 <class 'UserWarning'>,
 <class 'ValueError'>,
 <class 'Warning'>,
 <class 'OSError'>,
 <class 'ZeroDivisionError'>,
 <class '_frozen_importlib.BuiltinImporter'>,
 <class 'bool'>,
 <class 'bytearray'>,
 <class 'bytes'>,
 <class 'classmethod'>,
 <class 'complex'>,
 <class 'dict'>,
 <class 'enumerate'>,
 <class 'filter'>,
 <class 'float'>,
 <class 'frozenset'>,
 <class 'int'>,
 <class 'list'>,
 <class 'map'>,
 <class 'memoryview'>,
 <class 'object'>,
 <class 'property'>,
 <class 'range'>,
 <class 'reversed'>,
 <class 'set'>,
 <class 'slice'>,
 <class 'staticmethod'>,
 <class 'str'>,
 <class 'super'>,
 <class 'tuple'>,
 <class 'type'>,
 <class 'zip'>]

你可以这样做：

>>> a = "foo"
>>> type(a) in builtin_types 
True

如何获得所有Python类型的列表（以编程方式）？

3 个答案: