Python – singledispatch decorator

使用 functools.singledispatch 可以讓程式更容易閱讀,來看以下2個範例.

測試環境為 CentOS 8 x86_64 , 參考範例 – https://towardsdatascience.com/simplify-your-functions-with-functools-partial-and-singledispatch-b7071f7543bb

Function

[root@localhost ~]# vi fun.py
def process_data(data):
    if isinstance(data, dict):
        process_dict(data)
    elif isinstance(data, list):
        process_list(data)
    else:
        print("Unknow type")

def process_dict(data: dict):
    print("Dict is processed")

def process_list(data: list):
    print("List is processed")

process_data([1,2,3])
process_data(1)
process_data({"a":1 ,"b":2})

執行結果

[root@localhost ~]# python3 fun.py
List is processed
Unknow type
Dict is processed

functools.singledispatch

將上面程式改成使用 singledispatch 這樣就可以做 Function Overloading .

1. 使用 decorator @singledispatch 在 function_name.
2. 使用 decorator @functio_name.register(Data Type) 依據不同資料型別來完成不同工作.

[root@localhost ~]# vi func.py 
from functools import singledispatch

@singledispatch 
def process_data(data):
    print("Unknow type")

@process_data.register(dict)
def _(data):
    print("Dict is processed")

@process_data.register(list)
def _(data):
    print("List is processed")

process_data([1,2,3])
process_data(1)
process_data({"a":1 ,"b":2})

執行結果

[root@localhost ~]# python3 func.py 
List is processed
Unknow type
Dict is processed