Python __str__ and lists

Question

In Java, if I call List.toString(), it will automatically call the toString() method on each object inside the List. For example, if my list contains objects o1, o2, and o3, list.toString() would look something like this:

"[" + o1.toString() + ", " + o2.toString() + ", " + o3.toString() + "]"

Is there a way to get similar behavior in Python? I implemented a __str__() method in my class, but when I print out a list of objects, using:

print 'my list is %s'%(list)

it looks something like this:

[<__main__.cell instance at 0x2a955e95f0>, <__main__.cell instance at 0x2a955e9638>, <__main__.cell instance at 0x2a955e9680>]

how can I get python to call my __str__() automatically for each element inside the list (or dict for that matter)?

Answer 1

Calling string on a python list calls the __repr__ method on each element inside. For some items, __str__ and __repr__ are the same. If you want that behavior, do:

def __str__(self):
    ...
def __repr__(self):
    return self.__str__()

Answer 2

You can use a list comprehension to generate a new list with each item str()'d automatically:

print([str(item) for item in mylist])