Question

I have an array of objects. I am interested in writing a function that will find a specific object in a list and return a reference to it.

Imagine the following code snippet was possible:

list1 = [1,2,3]
def find(q):
    return q[0]
a = find(list1) 
a = 0 # This should change the object that "a" is referencing to.
print list1 # [0, 2, 3] is desired as result.

It is easy to do with pointers in C++, but how can I do it in python?

Answer 1

To achieve exact same semantics may not be possible but something similar can be achieved by a proxy with get/set methods, though I am not clear exactly what and why you needed this, so final solution could be much more complex or simple, anyway here is my solution

def find(q):
    return Pointer(q, 0)

class Pointer(object):
    def __init__(self, alist, index):
        self.alist = alist
        self.index = index

    def get(self):
        return self.alist[self.index]

    def set(self, value):
        self.alist[self.index] = value

list1 = [1, 2, 3]     
p = find(list1)
p.set(0)
print list1

output:

[0, 2, 3]