使用字符串列表执行带参数的函数

Question

我想使用列表对象按名称调用函数，将参数传递给每个函数，而列表则在循环中使用。 必须将这些函数引用为字符串，就像在实际脚本中一样，这些字符串是通过命令行输入获取的。

功能

我具有以下功能：

 def sum_a(x):
     x + 1000


 def sum_b(x):
     x + 100


 def sum_c(x):
     x + 1

呼叫

我想为sum_a执行功能sum_c和x = 9。

方法

functions_to_call = ['sum_a', 'sum_c']
x = 9
for each_call in functions_to_call:
    getattr(globals(), each_call)()

问题

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-14-9f12b9113b60> in <module>()
      1 for each_call in functions_to_call:
----> 2     getattr(globals(), each_call)()
      3

AttributeError: 'dict' object has no attribute 'sum_a'

Answer 1

您可以通过函数名称来引用它们。它们的行为就像变量。

functions_to_call = [sum_a, sum_c]
x = 9
for each_call in functions_to_call:
    each_call(x)

如果要按名称引用功能：

functions_to_call = ['sum_a', 'sum_c']
x = 9
for each_call in functions_to_call:
    globals()[each_call](x)

Answer 2

最好直接引用这些函数：

functions_to_call = [sum_a, sum_c]
x = 9
for f in functions_to_call:
    f(x)

对于您的特定问题，getattr在字典中搜索那些属性，但是您想要访问字典，为此您可以使用operator.itemgetter：

>>> from operator import itemgetter
>>> x = 10
>>> itemgetter("x")(globals())
10

最终版本如下：

from operator import itemgetter
functions_to_call = ['sum_a', 'sum_c']
x = 9
for each_call in map(itemgetter, functions_to_call):
    each_call(globals())(x)

无论如何，您不应该这样使用globals，最好使用寻址字典：

funcs = {
    "sum_a" : sum_a,
    "sum_c" : sum_c
}
    functions_to_call = ['sum_a', 'sum_c']
    x = 9
    for each_call in functions_to_call:
        funcs.get(each_call, lambda *_: print("Selected function do not exist"))(x)