Extending Python - variable sized arrays?

Skip Montanaro skip at pobox.com
Wed Oct 17 00:47:50 CEST 2001


    Paul> Use the apply function.  apply(f, [1,2,3]) is the same as f(1,2,3).

In recent versions (>= 2.0 I think), you can dispense with apply() in many
situations:

    >>> def f(*args):
    ...   print args
    ... 
    >>> apply(f, (1,2,3))
    (1, 2, 3)
    >>> f(*(1,2,3))
    (1, 2, 3)

Same technique works for keyword args:

    >>> def g(**kwds):
    ...   for k in kwds:
    ...     print (k, kwds[k])
    ... 
    >>> apply(g, (), {"a":1, "b":2})
    ('a', 1)
    ('b', 2)
    >>> g(**{"a":1, "b":2})
    ('a', 1)
    ('b', 2)

Generally speaking, neither technique is used with literals as I've shown,
but to pass variable arg lists along to other varargs functions:

    class Foo(Bar):
        def __init__(self,a,b,c,*args,**kwds):
            Bar.__init__(self,a,b,c,*args,**kwds)
            ...

-- 
Skip Montanaro (skip at pobox.com)
http://www.mojam.com/
http://www.musi-cal.com/




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