python-是否可以创建"def"列表? [英] python - Is it possible to create a list of "def"?

问题描述

我想知道是否可以创建"def"列表，连接20个按钮的列表以及为每个按钮设置不同的回调.

I wonder if it's possible to create a list of "def", to connect a list of 20 buttons, and to have a different callback for each button.

谢谢

推荐答案

def只是将名称绑定到函数/闭包的常规语句.例如，您可以编写

def in Python is just a regular statement that binds a name to a function/closure. For example you can write

flist = []
for i in range(30):
    def func(x, i=i):
        print(x * i)
    flist.append(func)

之后，flist[7](6)将返回42.

棘手的部分只是上述声明中的i=i.之所以需要这样做，是因为闭包捕获了变量，而不是当前的变量值.没有i=i，所有功能都将使用与循环相同的变量i.

The tricky part is only i=i in the above declaration. This is needed because a closure caputures the variable, not the current variable value. Without that i=i all of the functions would be using the same variable i used for looping.

Python还对匿名函数提供了一些支持，因此在上述简单情况下，代码可以缩短为

Python also has some support for anonymous functions so in the above simple case the code could be shortened to

flist = []
for i in range(30):
    flist.append(lambda x, i=i: print(x * i))

但是lambda受限制(只是一个表达式，没有语句)

but lambdas are very limited (just a single expression, no statements)

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