将函数传递给Python中的类

Question

So I'm working on a class structure for a text-based menu. I need to create the menus and set the actions before actually running the code. So to avoid the function being called to early, I have created a class called Run which takes the given function and runs it. My problem is that I don't know how I should handle the arguments for the function. What I have so far, and which doesn't work is:

class Run:
    def __init__(self, func):
        self.func = func

    def execute(self):
        print('Running')
        self.func

def foo(*args):
    print(*args)

baz = Run(foo('bar'))

baz.execute()

Just to be clear I first want the function to run when I run baz.execute()

Answer 1

You are calling the function before you pass it to Run , so func is actually the result of calling it ( None , as it doesn't return anything). The minimal fix is:

class Run:

    def __init__(self, func, *args, **kwargs):
        self.func = func
        self.args = args
        self.kwargs = kwargs

    def execute(self):
        print('Running')
        self.func(*self.args, **self.kwargs)  # call func here


baz = Run(foo, 'bar')  # don't call func here
baz.execute()

However, you can just use functools.partial to do this, removing the need to maintain your own class and tack .execute onto the eventual call (which you could also eliminate by renaming execute to __call__ :

>>> from functools import partial
>>> def foo(*args):
    print(*args)


>>> baz = partial(foo, 'bar')
>>> baz
functools.partial(<function foo at 0x1059c4400>, 'bar')
>>> baz()
bar