一个可以“按原样”使用的常见用例是重写一个类来创建一个类型(在其他方面与超类相同)，例如。

class Error(Exception):
    pass

因此，您可以引发并捕获Error异常。这里重要的是异常的类型，而不是内容。

Pass is usually helpful when you are writing code to design a game or something of that type , now as you proceed with the code , you would realize that , there are some functions you don't want to move ahead and want to leave it untouched and move further on with the code and then revisit the function later , but as you do so , the compiler would obviously thrown an error saying it isn't either recognized and all sorts of other things!! In this condition you use pass so that the compiler would simply neglect the function and move further on with the code !!

例如:

if __name__ = "__main__":
pass
print("Hello World!")

在这里，编译器将忽略if name部分，并按照指示打印Hello World !!

谢谢!

除了“我不想要任何东西到这里”的“主要”用途之外，我刚刚发现了一个，假设gen是一个迭代器:

i = 0
obj = None

for i, obj in enumerate(gen):
    pass

这将在一次传递中获得gen生成的最后一个对象和gen的长度。(有点类似于C语言中以分号结尾的while循环，仔细想想吧。)

你可以说pass意味着一个NOP(无操作)操作。看完这个例子，你就会清楚了:

C程序

#include<stdio.h>

void main()
{
    int age = 12;
  
    if( age < 18 )
    {
         printf("You are not adult, so you can't do that task ");
    }
    else if( age >= 18 && age < 60)
    {
        // I will add more code later inside it 
    }
    else
    {
         printf("You are too old to do anything , sorry ");
    }
}

现在你要怎么用Python写这个:

age = 12

if age < 18:

    print "You are not adult, so you can't do that task"

elif age >= 18 and age < 60:

else:

    print "You are too old to do anything , sorry "

但是您的代码会给出一个错误，因为在elif之后需要一个缩进的块。下面是pass关键字的作用。

age = 12

if age < 18:

    print "You are not adult, so you can't do that task"

elif age >= 18 and age < 60:
    
    pass

else:

    print "You are too old to do anything , sorry "

现在我想你们都清楚了。

正如书中所说，我只把它用作临时占位符，也就是说，

# code that does something to to a variable, var
if var == 2000:
    pass
else:
    var += 1

然后填充var == 2000的场景。

Pass指忽略…就是这么简单。如果给定的条件为真，并且下一个语句是通过的，它将忽略该值或迭代并继续执行下一行。

例子:

for i in range (1, 100):
    if i%2 == 0:
        pass
    else:
        print(i)

输出:输出1-100之间的所有奇数

这是因为一个偶数的模量等于零，因此它会忽略这个数字，继续下一个数字。由于奇数的模量不等于零，循环的else部分被执行并打印出来。