Python 自省指南

$ pythonPython 2.2.2 (#1, Oct 28 2002, 17:22:19)[GCC 3.2 (Mandrake Linux 9.0 3.2-1mdk)] on linux2Type "help", "copyright", "credits" or "license" for more information.>>>

>>> helpType help() for interactive help, or help(object) for help about object.

>>> help()Welcome to Python 2.2!  This is the online help utility.If this is your first time using Python, you should definitely check outthe tutorial on the Internet at http://www.python.org/doc/tut/.Enter the name of any module, keyword, or topic to get help on writingPython programs and using Python modules.  To quit this help utility andreturn to the interpreter, just type "quit".To get a list of available modules, keywords, or topics, type "modules","keywords", or "topics".  Each module also comes with a one-line summaryof what it does; to list the modules whose summaries contain a given wordsuch as "spam", type "modules spam".help>

help> keywordsHere is a list of the Python keywords.  Enter any keyword to get more help.and                 elif                global              orassert              else                if                  passbreak               except              import              printclass               exec                in                  raisecontinue            finally             is                  returndef                 for                 lambda              trydel                 from                not                 whilehelp> quitYou are now leaving help and returning to the Python interpreter.If you want to ask for help on a particular object directly from theinterpreter, you can type "help(object)".  Executing "help(‘string‘)"has the same effect as typing a particular string at the help> prompt.>>>

>>> help(‘modules‘)Please wait a moment while I gather a list of all available modules...BaseHTTPServer      cgitb               marshal             sndhdrBastion             chunk               math                socketCDROM               cmath               md5                 sreCGIHTTPServer       cmd                 mhlib               sre_compileCanvas              code                mimetools           sre_constants	<...>bisect              macpath             signal              xreadlinescPickle             macurl2path         site                xxsubtypecStringIO           mailbox             slgc (package)      zipfilecalendar            mailcap             smtpdcgi                 markupbase          smtplibEnter any module name to get more help.  Or, type "modules spam" to searchfor modules whose descriptions contain the word "spam".>>>

$ pythonPython 2.2.2 (#1, Oct 28 2002, 17:22:19)[GCC 3.2 (Mandrake Linux 9.0 3.2-1mdk)] on linux2Type "help", "copyright", "credits" or "license" for more information.>>> import sys>>> sys.executable‘/usr/local/bin/python‘

>>> sys.platform‘linux2‘

>>> sys.version‘2.2.2 (#1, Oct 28 2002, 17:22:19) \n[GCC 3.2 (Mandrake Linux 9.0 3.2-1mdk)]‘>>> sys.version_info(2, 2, 2, ‘final‘, 0)

>>> sys.maxint2147483647

>>> sys.argv[‘‘]

>>> sys.argv[0]‘/home/pobrien/Code/PyCrust/PyCrustApp.py‘

>>> sys.path[‘‘, ‘/home/pobrien/Code‘,‘/usr/local/lib/python2.2‘,‘/usr/local/lib/python2.2/plat-linux2‘,‘/usr/local/lib/python2.2/lib-tk‘,‘/usr/local/lib/python2.2/lib-dynload‘,‘/usr/local/lib/python2.2/site-packages‘]

>>> sys.modules{‘stat‘: <module ‘stat‘ from ‘/usr/local/lib/python2.2/stat.pyc‘>,‘__future__‘: <module ‘__future__‘ from ‘/usr/local/lib/python2.2/__future__.pyc‘>,‘copy_reg‘: <module ‘copy_reg‘ from ‘/usr/local/lib/python2.2/copy_reg.pyc‘>,‘posixpath‘: <module ‘posixpath‘ from ‘/usr/local/lib/python2.2/posixpath.pyc‘>,‘UserDict‘: <module ‘UserDict‘ from ‘/usr/local/lib/python2.2/UserDict.pyc‘>,‘signal‘: <module ‘signal‘ (built-in)>,‘site‘: <module ‘site‘ from ‘/usr/local/lib/python2.2/site.pyc‘>,‘__builtin__‘: <module ‘__builtin__‘ (built-in)>,‘sys‘: <module ‘sys‘ (built-in)>,‘posix‘: <module ‘posix‘ (built-in)>,‘types‘: <module ‘types‘ from ‘/usr/local/lib/python2.2/types.pyc‘>,‘__main__‘: <module ‘__main__‘ (built-in)>,‘exceptions‘: <module ‘exceptions‘ (built-in)>,‘os‘: <module ‘os‘ from ‘/usr/local/lib/python2.2/os.pyc‘>,‘os.path‘: <module ‘posixpath‘ from ‘/usr/local/lib/python2.2/posixpath.pyc‘>}

>>> help(‘modules keywords‘)Here is a list of matching modules.  Enter any module name to get more help.keyword - Keywords (from "graminit.c")

>>> import keyword>>> keyword.kwlist[‘and‘, ‘assert‘, ‘break‘, ‘class‘, ‘continue‘, ‘def‘, ‘del‘, ‘elif‘, ‘else‘,‘except‘, ‘exec‘, ‘finally‘, ‘for‘, ‘from‘, ‘global‘, ‘if‘, ‘import‘, ‘in‘, ‘is‘,‘lambda‘, ‘not‘, ‘or‘, ‘pass‘, ‘print‘, ‘raise‘, ‘return‘, ‘try‘, ‘while‘, ‘yield‘]

>>> dir(keyword)[‘__all__‘, ‘__builtins__‘, ‘__doc__‘, ‘__file__‘, ‘__name__‘,‘iskeyword‘, ‘keyword‘, ‘kwdict‘, ‘kwlist‘, ‘main‘]

>>> dir(sys)[‘__displayhook__‘, ‘__doc__‘, ‘__excepthook__‘, ‘__name__‘, ‘__stderr__‘,‘__stdin__‘, ‘__stdout__‘, ‘_getframe‘, ‘argv‘, ‘builtin_module_names‘,‘byteorder‘, ‘copyright‘, ‘displayhook‘, ‘exc_info‘, ‘exc_type‘, ‘excepthook‘,‘exec_prefix‘, ‘executable‘, ‘exit‘, ‘getdefaultencoding‘, ‘getdlopenflags‘,‘getrecursionlimit‘, ‘getrefcount‘, ‘hexversion‘, ‘last_traceback‘,‘last_type‘, ‘last_value‘, ‘maxint‘, ‘maxunicode‘, ‘modules‘, ‘path‘,‘platform‘, ‘prefix‘, ‘ps1‘, ‘ps2‘, ‘setcheckinterval‘, ‘setdlopenflags‘,‘setprofile‘, ‘setrecursionlimit‘, ‘settrace‘, ‘stderr‘, ‘stdin‘, ‘stdout‘,‘version‘, ‘version_info‘, ‘warnoptions‘]

>>> dir()[‘__builtins__‘, ‘__doc__‘, ‘__name__‘, ‘keyword‘, ‘sys‘]

>>> __builtins__<module ‘__builtin__‘ (built-in)>

>>> dir(__builtins__)[‘ArithmeticError‘, ‘AssertionError‘, ‘AttributeError‘, ‘DeprecationWarning‘,‘EOFError‘, ‘Ellipsis‘, ‘EnvironmentError‘, ‘Exception‘, ‘False‘,‘FloatingPointError‘, ‘IOError‘, ‘ImportError‘, ‘IndentationError‘,‘IndexError‘, ‘KeyError‘, ‘KeyboardInterrupt‘, ‘LookupError‘, ‘MemoryError‘,‘NameError‘, ‘None‘, ‘NotImplemented‘, ‘NotImplementedError‘, ‘OSError‘,‘OverflowError‘, ‘OverflowWarning‘, ‘ReferenceError‘, ‘RuntimeError‘,‘RuntimeWarning‘, ‘StandardError‘, ‘StopIteration‘, ‘SyntaxError‘,‘SyntaxWarning‘, ‘SystemError‘, ‘SystemExit‘, ‘TabError‘, ‘True‘, ‘TypeError‘,‘UnboundLocalError‘, ‘UnicodeError‘, ‘UserWarning‘, ‘ValueError‘, ‘Warning‘,‘ZeroDivisionError‘, ‘_‘, ‘__debug__‘, ‘__doc__‘, ‘__import__‘, ‘__name__‘,‘abs‘, ‘apply‘, ‘bool‘, ‘buffer‘, ‘callable‘, ‘chr‘, ‘classmethod‘, ‘cmp‘,‘coerce‘, ‘compile‘, ‘complex‘, ‘copyright‘, ‘credits‘, ‘delattr‘, ‘dict‘,‘dir‘, ‘divmod‘, ‘eval‘, ‘execfile‘, ‘exit‘, ‘file‘, ‘filter‘, ‘float‘,‘getattr‘, ‘globals‘, ‘hasattr‘, ‘hash‘, ‘help‘, ‘hex‘, ‘id‘, ‘input‘, ‘int‘,‘intern‘, ‘isinstance‘, ‘issubclass‘, ‘iter‘, ‘len‘, ‘license‘, ‘list‘,‘locals‘, ‘long‘, ‘map‘, ‘max‘, ‘min‘, ‘object‘, ‘oct‘, ‘open‘, ‘ord‘, ‘pow‘,‘property‘, ‘quit‘, ‘range‘, ‘raw_input‘, ‘reduce‘, ‘reload‘, ‘repr‘, ‘round‘,‘setattr‘, ‘slice‘, ‘staticmethod‘, ‘str‘, ‘super‘, ‘tuple‘, ‘type‘, ‘unichr‘,‘unicode‘, ‘vars‘, ‘xrange‘, ‘zip‘]

>>> dir(‘this is a string‘)[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__doc__‘, ‘__eq__‘,‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, ‘__getslice__‘, ‘__gt__‘,‘__hash__‘, ‘__init__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__mul__‘, ‘__ne__‘,‘__new__‘, ‘__reduce__‘, ‘__repr__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__str__‘,‘capitalize‘, ‘center‘, ‘count‘, ‘decode‘, ‘encode‘, ‘endswith‘, ‘expandtabs‘,‘find‘, ‘index‘, ‘isalnum‘, ‘isalpha‘, ‘isdigit‘, ‘islower‘, ‘isspace‘,‘istitle‘, ‘isupper‘, ‘join‘, ‘ljust‘, ‘lower‘, ‘lstrip‘, ‘replace‘, ‘rfind‘,‘rindex‘, ‘rjust‘, ‘rstrip‘, ‘split‘, ‘splitlines‘, ‘startswith‘, ‘strip‘,‘swapcase‘, ‘title‘, ‘translate‘, ‘upper‘, ‘zfill‘]

dir(42)   # Integer (and the meaning of life)dir([])   # List (an empty list, actually)dir(())   # Tuple (also empty)dir({})   # Dictionary (ditto)dir(dir)  # Function (functions are also objects)

>>> class Person(object):...     """Person class."""...     def __init__(self, name, age):...         self.name = name...         self.age = age...     def intro(self):...         """Return an introduction."""...         return "Hello, my name is %s and I‘m %s." % (self.name, self.age)...>>> bob = Person("Robert", 35)   # Create a Person instance>>> joe = Person("Joseph", 17)   # Create another>>> joe.sport = "football"       # Assign a new attribute to one instance>>> dir(Person)      # Attributes of the Person class[‘__class__‘, ‘__delattr__‘, ‘__dict__‘, ‘__doc__‘, ‘__getattribute__‘,‘__hash__‘, ‘__init__‘, ‘__module__‘, ‘__new__‘, ‘__reduce__‘, ‘__repr__‘,‘__setattr__‘, ‘__str__‘, ‘__weakref__‘, ‘intro‘]>>> dir(bob)         # Attributes of bob[‘__class__‘, ‘__delattr__‘, ‘__dict__‘, ‘__doc__‘, ‘__getattribute__‘,‘__hash__‘, ‘__init__‘, ‘__module__‘, ‘__new__‘, ‘__reduce__‘, ‘__repr__‘,‘__setattr__‘, ‘__str__‘, ‘__weakref__‘, ‘age‘, ‘intro‘, ‘name‘]>>> dir(joe)         # Note that joe has an additional attribute[‘__class__‘, ‘__delattr__‘, ‘__dict__‘, ‘__doc__‘, ‘__getattribute__‘,‘__hash__‘, ‘__init__‘, ‘__module__‘, ‘__new__‘, ‘__reduce__‘, ‘__repr__‘,‘__setattr__‘, ‘__str__‘, ‘__weakref__‘, ‘age‘, ‘intro‘, ‘name‘, ‘sport‘]>>> bob.intro()      # Calling bob‘s intro method"Hello, my name is Robert and I‘m 35.">>> dir(bob.intro)   # Attributes of the intro method[‘__call__‘, ‘__class__‘, ‘__cmp__‘, ‘__delattr__‘, ‘__doc__‘, ‘__get__‘,‘__getattribute__‘, ‘__hash__‘, ‘__init__‘, ‘__new__‘, ‘__reduce__‘,‘__repr__‘, ‘__setattr__‘, ‘__str__‘, ‘im_class‘, ‘im_func‘, ‘im_self‘]

>>> print __builtins__.__doc__   # Module docstringBuilt-in functions, exceptions, and other objects.Noteworthy: None is the `nil‘ object; Ellipsis represents `...‘ in slices.

>>> Person.__doc__         # Class docstring‘Person class.‘>>> Person.intro.__doc__   # Class method docstring‘Return an introduction.‘

>>> print dir.__doc__   # Function docstringdir([object]) -> list of stringsReturn an alphabetized list of names comprising (some of) the attributesof the given object, and of attributes reachable from it:No argument:  the names in the current scope.Module object:  the module attributes.Type or class object:  its attributes, and recursively the attributes of    its bases.Otherwise:  its attributes, its class‘s attributes, and recursively the    attributes of its class‘s base classes.

$ pythonPython 2.2.2 (#1, Oct 28 2002, 17:22:19)[GCC 3.2 (Mandrake Linux 9.0 3.2-1mdk)] on linux2Type "help", "copyright", "credits" or "license" for more information.>>> dir()                # The dir() function[‘__builtins__‘, ‘__doc__‘, ‘__name__‘]>>> directory = dir      # Create a new variable>>> directory()          # Works just like the original object[‘__builtins__‘, ‘__doc__‘, ‘__name__‘, ‘directory‘]>>> dir.__name__         # What‘s your name?‘dir‘>>> directory.__name__   # My name is the same‘dir‘>>> __name__             # And now for something completely different‘__main__‘

if __name__ == ‘__main__‘:    # Do something appropriate here, like calling a    # main() function defined elsewhere in this module.    main()else:    # Do nothing. This module has been imported by another    # module that wants to make use of the functions,    # classes and other useful bits it has defined.

>>> import types>>> print types.__doc__Define names for all type symbols known in the standard interpreter.Types that are part of optional modules (e.g. array) are not listed.>>> dir(types)[‘BufferType‘, ‘BuiltinFunctionType‘, ‘BuiltinMethodType‘, ‘ClassType‘,‘CodeType‘, ‘ComplexType‘, ‘DictProxyType‘, ‘DictType‘, ‘DictionaryType‘,‘EllipsisType‘, ‘FileType‘, ‘FloatType‘, ‘FrameType‘, ‘FunctionType‘,‘GeneratorType‘, ‘InstanceType‘, ‘IntType‘, ‘LambdaType‘, ‘ListType‘,‘LongType‘, ‘MethodType‘, ‘ModuleType‘, ‘NoneType‘, ‘ObjectType‘, ‘SliceType‘,‘StringType‘, ‘StringTypes‘, ‘TracebackType‘, ‘TupleType‘, ‘TypeType‘,‘UnboundMethodType‘, ‘UnicodeType‘, ‘XRangeType‘, ‘__builtins__‘, ‘__doc__‘,‘__file__‘, ‘__name__‘]>>> s = ‘a sample string‘>>> type(s)<type ‘str‘>>>> if type(s) is types.StringType: print "s is a string"...s is a string>>> type(42)<type ‘int‘>>>> type([])<type ‘list‘>>>> type({})<type ‘dict‘>>>> type(dir)<type ‘builtin_function_or_method‘>

>>> print id.__doc__id(object) -> integerReturn the identity of an object.  This is guaranteed to be unique amongsimultaneously existing objects.  (Hint: it‘s the object‘s memory address.)>>> alist = [1, 2, 3]>>> blist = [1, 2, 3]>>> clist = blist>>> clist[1, 2, 3]>>> blist[1, 2, 3]>>> alist[1, 2, 3]>>> id(alist)145381412>>> id(blist)140406428>>> id(clist)140406428>>> alist is blist    # Returns 1 if True, 0 if False0>>> blist is clist    # Ditto1>>> clist.append(4)   # Add an item to the end of the list>>> clist[1, 2, 3, 4]>>> blist             # Same, because they both point to the same object[1, 2, 3, 4]>>> alist             # This one only looked the same initially[1, 2, 3]

>>> print hasattr.__doc__hasattr(object, name) -> BooleanReturn whether the object has an attribute with the given name.(This is done by calling getattr(object, name) and catching exceptions.)>>> print getattr.__doc__getattr(object, name[, default]) -> valueGet a named attribute from an object; getattr(x, ‘y‘) is equivalent to x.y.When a default argument is given, it is returned when the attribute doesn‘texist; without it, an exception is raised in that case.>>> hasattr(id, ‘__doc__‘)1>>> print getattr(id, ‘__doc__‘)id(object) -> integerReturn the identity of an object.  This is guaranteed to be unique amongsimultaneously existing objects.  (Hint: it‘s the object‘s memory address.)

>>> print callable.__doc__callable(object) -> BooleanReturn whether the object is callable (i.e., some kind of function).Note that classes are callable, as are instances with a __call__() method.>>> callable(‘a string‘)0>>> callable(dir)1

>>> print isinstance.__doc__isinstance(object, class-or-type-or-tuple) -> BooleanReturn whether an object is an instance of a class or of a subclass thereof.With a type as second argument, return whether that is the object‘s type.The form using a tuple, isinstance(x, (A, B, ...)), is a shortcut forisinstance(x, A) or isinstance(x, B) or ... (etc.).>>> isinstance(42, str)0>>> isinstance(‘a string‘, int)0>>> isinstance(42, int)1>>> isinstance(‘a string‘, str)1

>>> print issubclass.__doc__issubclass(C, B) -> BooleanReturn whether class C is a subclass (i.e., a derived class) of class B.>>> class SuperHero(Person):   # SuperHero inherits from Person......     def intro(self):       # but with a new SuperHero intro...         """Return an introduction."""...         return "Hello, I‘m SuperHero %s and I‘m %s." % (self.name, self.age)...>>> issubclass(SuperHero, Person)1>>> issubclass(Person, SuperHero)0>>>

>>> def interrogate(item):...     """Print useful information about item."""...     if hasattr(item, ‘__name__‘):...         print "NAME:    ", item.__name__...     if hasattr(item, ‘__class__‘):...         print "CLASS:   ", item.__class__.__name__...     print "ID:      ", id(item)...     print "TYPE:    ", type(item)...     print "VALUE:   ", repr(item)...     print "CALLABLE:",...     if callable(item):...         print "Yes"...     else:...         print "No"...     if hasattr(item, ‘__doc__‘):...         doc = getattr(item, ‘__doc__‘)... 	doc = doc.strip()   # Remove leading/trailing whitespace.... 	firstline = doc.split(‘\n‘)[0]... 	print "DOC:     ", firstline...>>> interrogate(‘a string‘)     # String objectCLASS:    strID:       141462040TYPE:     <type ‘str‘>VALUE:    ‘a string‘CALLABLE: NoDOC:      str(object) -> string>>> interrogate(42)             # Integer objectCLASS:    intID:       135447416TYPE:     <type ‘int‘>VALUE:    42CALLABLE: NoDOC:      int(x[, base]) -> integer>>> interrogate(interrogate)    # User-defined function objectNAME:     interrogateCLASS:    functionID:       141444892TYPE:     <type ‘function‘>VALUE:    <function interrogate at 0x86e471c>CALLABLE: YesDOC:      Print useful information about item.