Python-getattr()的使用

getatter()通过方法名字符串调用方法，这个方法最主要的作用就是实现反射机制，也就是说可以通过字符串获取方法实例，这样就可以把一个类可能要调用的方法放到配置文件里，需要的时候进行动态加载。

1: 可以从类中获取属性和函数

新建test.py文件,代码如下:

# encoding:utf-8
import sys

class GetText():
    def __init__(self):
        pass

    @staticmethod
    def A():
        print("this is a staticmethod function")

    def B(self):
        print("this is a func")
    c = "cc desc"

if __name__ == '__main__':
    print(sys.modules[__name__])  # <module '__main__' from 'D:/脚本项目/lianxi/clazz/test.py'>
    print(GetText)   #  <class '__main__.GetText'>
    # 获取函数
    print(getattr(GetText, "A"))   # <function GetText.A at 0x00000283C2B75798>
    # 获取函数返回值
    getattr(GetText, "A")()    # this is a staticmethod function
    getattr(GetText(), "A")()   # this is a staticmethod function

    print(getattr(GetText, "B"))    # <function GetText.B at 0x000001371BF55798>
    # 非静态方法不可用
    # getattr(GetText, "B")()
    getattr(GetText(), "B")()     # this is a func
    print(getattr(GetText, "c"))  # cc desc
    print(getattr(GetText(), "c"))   # cc desc

 2:从模块中获取类(通过类名字符串得到类对象)

新建test1.py，代码如下:

#encoding:utf-8
import sys
import test
print(sys.modules[__name__])

# 从模块中获取类对象
class_name = getattr(test, "GetText")
print(class_name)    #  <class 'test.GetText'>

# 调用类的属性和函数
print(getattr(class_name, "A"))    # <function GetText.A at 0x000001D637365678>
# 获取函数返回值
getattr(class_name, "A")()    # this is a staticmethod function
getattr(class_name(), "A")()   # this is a staticmethod function

print(getattr(class_name(), "B"))   # <bound method GetText.B of <test.GetText object at 0x0000022D3B9EE348>>
# getattr(class_name, "B")()   非静态方法不可用
getattr(class_name(), "B")()    # this is a func

# 获取属性值
print(getattr(class_name, "c"))    # cc desc
print(getattr(class_name(), "c"))    # cc desc