Python 2.7 quick reference |  |
Python 2.7 quick reference | |
The purpose of the dir() function is to find
out what names are defined in a given namespace, and return a
list of those names. If called without arguments, it returns
a list of the names defined in the local namespace. This
function can be very handy for finding out what items are in a
module or class.
Certain special names are found in most or all namespaces:
__doc__ is present in every namespace.
Initially None, you can store
documentation there.
__name__ is the name of the current
module (minus the .py extension).
In the top-level script or in conversational mode, this
name is set to the string '__main__'.
__builtins__ is a list of the names of
all built-in functions and variables.
In this example sequence, we'll show you what is in the global
namespace just after starting up Python. Then we'll import
the math module and display its names.
>>> dir() ['__builtins__', '__doc__', '__name__'] >>> x=5; forkTail='Tyrannus' >>> dir() ['__builtins__', '__doc__', '__name__', 'forkTail', 'x'] >>> print __doc__ None >>> print __name__ __main__ >>> import math >>> print math.__name__ math >>> dir(math) ['__doc__', '__file__', '__name__', 'acos', 'asin', 'atan', 'atan2', 'ceil' , 'cos', 'cosh', 'degrees', 'e', 'exp', 'fabs', 'floor', 'fmod', 'frexp', ' hypot', 'ldexp', 'log', 'log10', 'modf', 'pi', 'pow', 'radians', 'sin', 'si nh', 'sqrt', 'tan', 'tanh'] >>> print math.__doc__ This module is always available. It provides access to the mathematical functions defined by the C standard. >>> print math.log10.__doc__ log10(x) -> the base 10 logarithm of x. >>> print __builtins__ <module '__builtin__' (built-in)> >>> for k, name in enumerate(dir(__builtins__)): ... if (k%4)==3: print ... print name, ... ArithmeticError AssertionError AttributeError BaseException BufferError BytesWarning DeprecationWarning EOFError Ellipsis EnvironmentError Exception False FloatingPointError FutureWarning GeneratorExit IOError ImportError ImportWarning IndentationError IndexError KeyError KeyboardInterrupt LookupError MemoryError NameError None NotImplemented NotImplementedError OSError OverflowError PendingDeprecationWarning ReferenceError RuntimeError RuntimeWarning StandardError StopIteration SyntaxError SyntaxWarning SystemError SystemExit TabError True TypeError UnboundLocalError UnicodeDecodeError UnicodeEncodeError UnicodeError UnicodeTranslateError UnicodeWarning UserWarning ValueError Warning ZeroDivisionError _ __debug__ __doc__ __import__ __name__ __package__ abs all any apply basestring bin bool buffer bytearray bytes callable chr classmethod cmp coerce compile complex copyright credits delattr dict dir divmod enumerate eval execfile exit file filter float format frozenset getattr globals hasattr hash help hex id input int intern isinstance issubclass iter len license list locals long map max min next object oct open ord pow print property quit range raw_input reduce reload repr reversed round set setattr slice sorted staticmethod str sum super tuple type unichr unicode vars xrange zip