The resulting list is sorted alphabetically. For example:
>>> import struct
- >>> dir() # doctest: +SKIP
+ >>> dir() # show the names in the module namespace
['__builtins__', '__doc__', '__name__', 'struct']
- >>> dir(struct) # doctest: +NORMALIZE_WHITESPACE
+ >>> dir(struct) # show the names in the struct module
['Struct', '__builtins__', '__doc__', '__file__', '__name__',
'__package__', '_clearcache', 'calcsize', 'error', 'pack', 'pack_into',
'unpack', 'unpack_from']
- >>> class Foo:
- ... def __dir__(self):
- ... return ["kan", "ga", "roo"]
- ...
- >>> f = Foo()
- >>> dir(f)
- ['ga', 'kan', 'roo']
+ >>> class Shape(object):
+ def __dir__(self):
+ return ['area', 'perimeter', 'location']
+ >>> s = Shape()
+ >>> dir(s)
+ ['area', 'perimeter', 'location']
.. note::
:meth:`__next__` method of the iterator returned by :func:`enumerate` returns a
tuple containing a count (from *start* which defaults to 0) and the
corresponding value obtained from iterating over *iterable*.
- :func:`enumerate` is useful for obtaining an indexed series: ``(0, seq[0])``,
- ``(1, seq[1])``, ``(2, seq[2])``, .... For example:
- >>> for i, season in enumerate(['Spring', 'Summer', 'Fall', 'Winter']):
- ... print(i, season)
- 0 Spring
- 1 Summer
- 2 Fall
- 3 Winter
+ >>> for i, season in enumerate('Spring Summer Fall Winter'.split(), start=1):
+ print(i, season)
+ 1 Spring
+ 2 Summer
+ 3 Fall
+ 4 Winter
+
+ Equivalent to::
+
+ def enumerate(sequence, start=0):
+ n = start
+ for elem in sequence:
+ yield n, elem
+ n += 1
.. function:: eval(expression, globals=None, locals=None)
One useful application of the second form of :func:`iter` is to read lines of
a file until a certain line is reached. The following example reads a file
- until ``"STOP"`` is reached: ::
+ until the :meth:`readline` method returns an empty string::
- with open("mydata.txt") as fp:
- for line in iter(fp.readline, "STOP"):
+ with open('mydata.txt') as fp:
+ for line in iter(fp.readline, ''):
process_line(line)
It can be called either on the class (such as ``C.f()``) or on an instance (such
as ``C().f()``). The instance is ignored except for its class.
- Static methods in Python are similar to those found in Java or C++. For a more
- advanced concept, see :func:`classmethod` in this section.
+ Static methods in Python are similar to those found in Java or C++. Also see
+ :func:`classmethod` for a variant that is useful for creating alternate class
+ constructors.
For more information on static methods, consult the documentation on the
standard type hierarchy in :ref:`types`.
references. The zero argument form automatically searches the stack frame
for the class (``__class__``) and the first argument.
+ For practical suggestions on how to design cooperative classes using
+ :func:`super`, see `guide to using super()
+ <http://rhettinger.wordpress.com/2011/05/26/super-considered-super/>`_.
+
.. function:: tuple([iterable])