Scopes and Arguments
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Arbitrary Arguments Examples
>>> def f(*args): print args
...
>>> f()
()
>>> f(1)
(1,)
>>> f(1,2,3,4)
(1, 2, 3, 4)
>>>
>>> def f(**args): print args
...
>>> f()
{}
>>> f(a=1,b=2)
{'a': 1, 'b': 2}
>>>
>>> def f(a, *pargs, **kargs): print a, pargs, kargs
...
>>> f(1,2,3,x=1,y=2)
1 (2, 3) {'y': 2, 'x': 1}
>>>
>>> def multiple(x,y):
... x = 2
... y = [3,4]
... return x,y
...
>>> X = 1
>>> L = [1,2]
>>> X, L = multiple(X,L)
>>> X, L
(2, [3, 4])
>>>
>>> def f(a,b,c): print a,b,c
...
>>> f(1,2,30)
1 2 30
>>> f(c=30,b=22,a=11)
11 22 30
>>> f(111,c=333,b=222)
111 222 333
>>>
>>> def f(a, b=2, c=3): print a,b,c
...
>>> f(11)
11 2 3
>>> f(a = 111)
111 2 3
>>> f(1,4)
1 4 3
>>> f(1,4,5)
1 4 5
>>> f(1,c=66)
1 2 66
>>>
>>> X = 99
>>> def func(Y):
... Z = X + Y
... return Z
...
>>> func(1)
100
>>> import __builtin__
>>> dir(__builtin__)
['ArithmeticError', 'AssertionError', 'AttributeError', 'DeprecationWarning', 'E
OFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False', 'FloatingPointEr
ror', 'FutureWarning', 'IOError', 'ImportError', 'IndentationError', 'IndexError
', 'KeyError', 'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', '
None', 'NotImplemented', 'NotImplementedError', 'OSError', 'OverflowError', 'Ove
rflowWarning', 'PendingDeprecationWarning', 'ReferenceError', 'RuntimeError', 'R
untimeWarning', 'StandardError', 'StopIteration', 'SyntaxError', 'SyntaxWarning'
, 'SystemError', 'SystemExit', 'TabError', 'True', 'TypeError', 'UnboundLocalErr
or', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError', 'UnicodeTransla
teError', 'UserWarning', 'ValueError', 'Warning', 'WindowsError', 'ZeroDivisionE
rror', '_', '__debug__', '__doc__', '__import__', '__name__', 'abs', 'apply', 'b
asestring', 'bool', 'buffer', 'callable', 'chr', 'classmethod', 'cmp', 'coerce',
'compile', 'complex', 'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod
', 'enumerate', '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', 's
taticmethod', 'str', 'sum', 'super', 'tuple', 'type', 'unichr', 'unicode', 'vars
', 'xrange', 'zip']
>>> zip
<built-in function zip>
>>> X = 88
>>> def func():
... X = 99
...
>>> func()
>>> print X
88
>>>
>>> X = 88
>>> X
88
>>> def func():
... global X
... X = 9
...
>>> func()
>>> print X
9
>>>
>>> y, z = 1, 2
>>>
>>> def all_global():
... global x
... x = y + z
...
>>> x
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 'x' is not defined
>>> print x
Traceback (most recent call last):
File "<stdin>", line 1, in ?
NameError: name 'x' is not defined
>>> all_global()
>>> print x
3
>>>
>>> def f1():
... x = 88
... def f2():
... print x
... f2()
...
>>> f1()
88
>>> def f1():
... x = 88
... def f2():
... print x
... return f2()
...
>>> action = f1()
88
>>> action()
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: 'NoneType' object is not callable
>>> def f1():
... x = 88
... def f2(x=x):
... print x
... f2()
...
>>> f1()
88
>>>
>>> def func():
... x = 4
... action = (lambda n: x ** n)
... return action
...
>>> x = func()
>>> print x(2)
16
>>> def f1():
... x = 99
... def f2():
... def f3():
... print x
... f3()
... f2()
...
>>> f1()
99
>>>
Arguments and Shared References
>>> def changer(x,y):
... x = 2
... y[0] = 'spam'
...
>>> X = 1
>>> L = [1,2]
>>> changer(X,L)
>>> X,L
(1, ['spam', 2])
>>>
>>> L = [1,2]
>>> changer(X,L[:]) # Pass a copy, so my L doest not change
>>> def changer(x,y):
... y = y[:]
... x = 2
... y[0] = 'spam'
...
>>> L = [1,2]
>>> changer(X, tuple(L))
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "<stdin>", line 4, in changer
TypeError: object doesn't support item assignment
# Pass a tuple, so changes are errors
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