python中@符号实例详解_python

#Example 1
def test(func):
    print("a")
    return func()
    
@test     #从这里可以看出@test等价于 test(xxx())
def xxx():
    print('Hello world!')

#Example 2
def FA(fn):
    def warp():
        return "<a>"+fn()+"<a>"
    return warp
def FB(fn):
    def warp():
        return "<b>"+fn()+"<b>"
    return warp
    
@FA         #相当于makebold(test1),也就是把当前函数作为入参传过去
def test1():
    return "test1"
 
@FB
def test2():
    return "test2"
    
@FA
@FB
def test3():     #函数和装饰器是倒着执行的，从下往上，从内而外，一层层执行
    return "test3"
    
print(test1())
print(test2())
print(test3())

#Example 3
class Mat(list):
    def __matmul__(self, B):
        A = self
        return Mat([[sum(A[i][k]*B[k][j] for k in range(len(B)))
                    for j in range(len(B[0])) ] for i in range(len(A))])
A = Mat([[1,3],[7,5]])
B = Mat([[6,8],[4,2]])
print(A @ B)