[Tutor] Apply()

[Bob Gailer]

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At 11:03 AM 2/5/2003 -0500, Jim Beckstrom wrote:
>An explanation of the use of apply(), please.

Mechanics: apply(function, sequence-of-positional-parameters, 
mapping-of-named-parameters)

This lets you write code that calls an arbitrary function with arbitrary 
parameters. Say you create a set of functions; they all expect the same 
parameters; they do different things. It is only at execution time that the 
program chooses one of these based on some conditions. Instead of a series 
of if ... elif statements you use apply to "apply" the chosen function to 
the arguments.

# define functions
def a1(b,c):blah blah
def a2(b,c):blah blah
...
# associate functions with some key
dict = (1:a1, 2:a2, ...}
# determine which function to use
func_key = result of some calculation or user input
# apply that function
apply(dict[func_key], (values for b and c))

#is equivalent to:
if func_key == 1:a1(values for b and c)
elif func_key == 2:a2(values for b and c)


Bob Gailer
mailto:ramrom@earthling.net
303 442 2625

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