dwstein dwstein - 1 month ago 16
Python Question

Python: how to refer to an instance name?

I'm collecting instances using the following code:

class Hand():
instances = []
def __init__(self):
Hand.instances.append(self)
self.value = 5

def do_something(self, a):
self.value = self.value * a

class Foo():
def __init__(self):
pass

def insty(self):
self.hand1 = Hand()
self.hand2 = Hand()


foo = Foo()
foo.insty()
print Hand.instances

for hand in Hand.instances:
print "how do I print the instance name?"


The last line is just a way to learn how to to access the instance name so i can call the 'do_something' method on each instance in order.

How do I access the instance name for each instance of Hand?

Answer

If you mean how to get hand1 from the instance you assigned to self.hand1, the answer is that you can't. When you do self.hand1 = Hand(), you tell the Foo object it has a Hand, but the Hand object has no knowledge that it has been assigned to a Foo. You could do this:

h = Hand()
self.bob = h
self.larry = h

Now what is the "name" of that Hand supposed to be? You assigned the same hand to both "bob" and "larry", so there's no way it can have a single unique name.

If you want to have a name for each hand, you need to tell the hand what name you want to give it. You would have to modify your Hand code to allow you to pass a name to the constructor, then create the Hand with Hand("some name").

You can of course give the hands "names" by assigning attributes on them:

self.hand1 = Hand()
self.hand1.name = "hand 1"

. . . but these names are not special or "automatic" in any way.

The bottom line is that if you want something to have a name, you need to decide how to handle that name. You need write your own code that gives it its name, and your own code that retrieves its name.