I would like to do something like the following:
def add(a, b):
#some code
def subtract(a, b):
#some code
operations = [add, subtract]
operations[0]( 5,3)
operations[1](5,3)
In python, is it possible to assign something like a function pointer?
Did you try it? What you wrote works exactly as written. Functions are first-class objects in Python.
Python has nothing called pointers, but your code works as written. Function are first-class objects, assigned to names, and used as any other value.
You can use this to implement a Strategy pattern, for example:
def the_simple_way(a, b):
# blah blah
def the_complicated_way(a, b):
# blah blah
def foo(way):
if way == 'complicated':
doit = the_complicated_way
else:
doit = the_simple_way
doit(a, b)
Or a lookup table:
def do_add(a, b):
return a+b
def do_sub(a, b):
return a-b
handlers = {
'add': do_add,
'sub': do_sub,
}
print handlers[op](a, b)
You can even grab a method bound to an object:
o = MyObject()
f = o.method
f(1, 2) # same as o.method(1, 2)
def foo(): ...; bar = foo then foo and bar are both names referring to a function. There is no difference between them. So if foo is a function, then why isn't bar a function?Just a quick note that most Python operators already have an equivalent function in the operator module.
