python风格规范之do not compare types, for exact checks use `is` / `is not`, for instance chec

规范错误/警告描述

PEP 8: E721 do not compare types, for exact checks use `is` / `is not`, for instance checks use `isinstance()`

规范错误描述(示例)

def check_type(input_message):
    if type(input_message) == str:
        print("{} is a string.".format(input_message))
    else:
        print("{} is not a string.".format(input_message))

规范错误认知

关于type不要做比较，更希望使用is/is not做精确的判断。也可使用方法isinstance()进行替代。

正确示例

# 正确示例1
def check_type(input_message):
    if type(input_message) is str:
        print("{} is a string.".format(input_message))
    else:
        print("{} is not a string.".format(input_message))

# 正确示例2
def check_type(input_message):
    if isinstance(input_message,str):
        print("{} is a string.".format(input_message))
    else:
        print("{} is not a string.".format(input_message))
        

$\text{Reference}$：
python - 风格规范