Python中的多方法

Multimethod基本上是指具有多个版本的函数，以参数的类型来区分。为了更好地理解，请考虑以下示例。

@multimethod
def sum(x: int, y: int):
    return x + y

@multimethod
def sum(x: str, y: str):
    return x+" "+y

The above example is similar to

def sum(x, y):
    
    if isinstance(x, int) and isinstance(y, int):
        return x + y
    
    elif isinstance(x, str) and isinstance(y, str):
        return x + ' ' + y

安装

在句法层面， Python不支持多重分派，但可以使用库扩展multimethod添加多重分派。要安装此库，请在终端中键入以下命令。

pip install multimethod

示例 1：

# Python program to demonstrate
# multimethods
  
  
from multimethod import multimethod
  
  
# Function that will be called
# for integer addition
@multimethod
def sum(x: int, y: int):
    return x + y
  
# Function that will be called
# for string addition
@multimethod
def sum(x: str, y: str):
    return x+" "+y
  
# Driver's code
print(sum(2, 3))
print(sum("Hello", "World"))

输出：

5
Hello World

示例 2：

# Python program to demonstrate
# multimethods
  
  
from multimethod import multimethod
  
  
class GFG(object):
      
    @multimethod
    def double(self, x: int):
        print(2 * x)
  
    @multimethod
    def double(self, x: complex):
        print("sorry, I don't like complex numbers")
          
# Driver Code
obj = GFG()
obj.double(3)
obj.double(6j)

输出：

6
sorry, I don't like complex numbers