Question

I want to be able to create a new instance of an object by calling a method on an already instantiated object. For example, I have the object:

organism = Organism()

I want to be able to call organism.reproduce() and have two objects of type Organism. My method at this point looks like this:

class Organism(object):
    def reproduce():
        organism = Organism()

and I’m pretty sure it doesn’t work (I’m not really even sure how to test it. I tried the gc method in this post). So how can I make my object create a copy of itself that’s accessible just like the first object I created (with organism = Organism())?

Answer 1

class Organism(object):
    def reproduce(self):
        #use self here to customize the new organism ...
        return Organism()

Another option — if the instance (self) isn’t used within the method:

class Organism(object):
    @classmethod
    def reproduce(cls):
        return cls()

This makes sure that Organisms produce more Organisms and (hypothetical Borgs which are derived from Organisms produce more Borgs).

A side benefit of not needing to use self is that this can now be called from the class directly in addition to being able to be called from an instance:

new_organism0 = Organism.reproduce()  # Creates a new organism
new_organism1 = new_organism0.reproduce()  # Also creates a new organism

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Finally, if both the instance (self) and the class (Organism or subclasses if called from a subclass) are used within the method:

class Organism(object):
    def reproduce(self):
        #use self here to customize the new organism ...
        return self.__class__()  # same as cls = type(self); return cls()

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In each case, you’d use it as:

organism = Organism()
new_organism = organism.reproduce()