python函数中可选参数的命名实践

发布于 2024-10-24 05:47:46 字数 235 浏览 1 评论 0 原文

可以给 python 函数中的可选参数指定与外部变量相同的名称吗？它似乎工作得很好，因为下面定义的函数 f 和 g 给出了相同的输出。然而，这是否被认为是不好的做法，并且在某些情况下会失败吗？

a = 1
def f(x,A=a): return x*A
def g(x,a=a): return x*a

print g(2)
>> 2
print g(2,a=2)
>> 4

原文

Is it OK to give the optional argument in a python function the same name as an outside variable?
It seems to work fine as functions f and g defined below give the same output. However, is this considered bad practice and does it fail in some cases?

a = 1
def f(x,A=a): return x*A
def g(x,a=a): return x*a

print g(2)
>> 2
print g(2,a=2)
>> 4

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

毁虫ゝ 2024-10-31 05:47:46

它会起作用，尽管它很容易有点令人困惑，但它是完全有效的。这是因为函数和函数调用发生在不同的命名空间中。因此，如果您编写：

def some_function(var1,var2=somevalue):  #var1 & var2 of functions namespace
    some things happening here

var1 = somevalue #mainspace var1
var2 = somevalue #mainspace var2
some_function(var1,var2=var2) 
#upper line: first var2 = from function, second var2 = from mainspace

它将起作用，因为主命名空间中的 var1 与函数命名空间中的 var1 是完全不同的变量。即使您看似在一行中使用了 var2 两次，some_function 的调用也将按所示方式工作。但正如你在解释时的困难中看到的那样，这样做会产生一些混乱，所以如果可以的话最好跳过这样的事情。 Python 相对于其他语言的主要优势之一是它的可读性，您应该通过您的编码风格来支持这一点。

命名变量 a 和其他变量 A 也是您应该避免的。阅读有关 python 中的命名约定在这里。

It will work, although it can easily be a bit confusing, it is perfectly valid. This is due to the fact that the function and the call to the function happen in different namespaces. So if you write:

def some_function(var1,var2=somevalue):  #var1 & var2 of functions namespace
    some things happening here

var1 = somevalue #mainspace var1
var2 = somevalue #mainspace var2
some_function(var1,var2=var2) 
#upper line: first var2 = from function, second var2 = from mainspace

it will work, as var1 in the main namespace is an entirely different variable than var1 in the functions namespace. And the call of some_function will work as shown, even if you -seemingly- use var2 twice in one line. But as you can see in the difficulties while explaining, there is some confusion arised by doing this, so better skip things like that if you can. One of Python's main advantages over some other languages is its readability, you should support that through your coding style.

And naming variables a and other variables A is something you should avoid too. Have a read about naming conventions in python here. and a read about namespaces here.