对象实例作为列表元素

Question

I've written the below on a whim after being reading about the "METHINKS IT IS LIKE A WEASEL" algorithm. What I expect to happen in pop_gen() is for ten instances of Gib to be created - each with a randomised name - and stored in the list popul. What I get instead is a list of instances with the same name. I think that I'm actually only creating one instance then referring to it ten times, but I can't figure out why - I've tried doing it with a for loop instead of a list comprehension, and passing randomised names as variables instead of randomising in the Gib class itself.

import random
import string

class Evolver:
    def __init__(self, input_text, chance):
        self.input_text = list(input_text)
        self.gib_text = [random.choice(chars) for c in self.input_text]
        self.chance = chance
        self.popul = []

    def pop_gen(self):
        temp_popul = [Gib(self.gib_text, self.chance) for i in range(10)]
        self.popul = temp_popul

class Gib:
    def __init__(self, gib_text, chance):
        self.name = self.mutator(gib_text, chance)
        self.score = 0

    def mutator(self, gib_text, chance):
        for c in range(len(gib_text)):
            if chance >= random.randint(1, 100):
                gib_text[c] = random.choice(chars)
        return gib_text

chars = string.uppercase

e = Evolver("TEST", 100)
e.pop_gen()

for p in e.popul:
    print p, p.name

Any and all help appreciated!

Answer 1

You're creating 10 seperate instances with the same name . Since Gib.name ends up being a list, when you mutate it in Gib.mutator , all references to that list see the change. When you create the Gib s in the first place, you pass them the same list ( self.gib_text ), so they all share the same list for a name and therefore they all end up with the same name (even if it gets mutated in Gib.mutator ). One workaround is to copy self.gib_text when you pass it to the initializer:

def pop_gen(self):
    temp_popul = [Gib(self.gib_text[:], self.chance) for i in range(10)]