Question

我有一个包含多种方法的类人口。

根据输入，我希望以给定的顺序在类Population的实例上运行方法。

在我想要达到的目标方面更加准确，与使用类似的东西完全相同：

stuff = input(" enter stuff ")

dico = {'stuff1':functionA, 'stuff2':functionC, 'stuff3':functionB, 'stuff4':functionD}

dico[stuff]()

除了functionA，functionB等......是方法而不是函数：

order_type = 'a'
class Population (object):
    def __init__(self,a):
        self.a = a

    def method1 (self):
        self.a = self.a*2
        return self

    def method2 (self):
        self.a += 2
        return self

    def method3 (self,b):
        self.a = self.a + b
        return self

if order_type=='a':
    order = {1:method1, 2:method2, 3:method3}
elif order_type=='b':
    order = {1:method2, 2:method1, 3:method3}
else :
    order = {1:method3, 2:method2, 3:method1}

my_pop = Population(3)

while iteration < 100:
    iteration +=1
    for i in range(len(order)):
        method_to_use = order[i]
        my_pop.method_to_use() # But obviously it doesn't work!

希望我的问题足够明确！请注意，我的方法之一需要两个参数

Answer 1

使用getattr：

order = {1:'method1', 2:'method2', 3:'method3'} #values are strings
...
method_to_use = order[i]
getattr(mypop, method_to_use)()

Answer 2

将实例显式作为第一个参数传递：

method_to_use = order[i]
method_to_use(my_pop)

完整的工作代码：

order_type = 'a'
class Population (object):
    def __init__(self,a):
        self.a = a

    def method1 (self):
        self.a = self.a*2
        return self

    def method2 (self):
        self.a += 2
        return self

    def method3 (self):
        self.a = 0
        return self

if order_type=='a':
    order = [Population.method1, Population.method2, Population.method3]
elif order_type=='b':
    order = [Population.method2, Population.method1, Population.method3]
else :
    order = [Population.method3, Population.method2, Population.method1]

my_pop = Population(3)

while iteration < 100:
    iteration +=1
    for method_to_use in order:
        method_to_use(my_pop)

如果要传递多个参数，只需使用*args语法：

if order_type=='a':
    order = [Population.method1, Population.method2, Population.method3]
    arguments = [(), (), (the_argument,)]
elif order_type=='b':
    order = [Population.method2, Population.method1, Population.method3]
    arguments = [(), (), (the_argument,)]
else :
    order = [Population.method3, Population.method2, Population.method1]
    arguments = [(the_argument, ), (), ()]

my_pop = Population(3)

while iteration < 100:
    iteration +=1
    for method_to_use, args in zip(order, arguments):
        method_to_use(my_pop, *args)

()是一个空元组，因此*args将扩展为无其他参数，而(the_argument,)是一个将元素传递给方法的1元素元组。

Answer 3

您可以使用operator.methodcaller：

from operator import methodcaller
method_to_use = methodcaller('method' + str(i))
method_to_use(my_pop)

使用字典来控制方法的流程

3 个答案: