编程►Python

Metaclass

文章目录

实现一个将类的属性全部转为大写的metaclass

What are metaclasses in Python?

  • 实现一个将类的属性全部转为大写的metaclass
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class UpperAttrMetaclass(type):
    def __new__(cls, clsname, bases, attrs):
        uppercase_attrs = {
            attr if attr.startswith('__') else attr.upper(): v
            for attr, v in attrs.items()
        }
        # return type(clsname, bases, uppercase_attrs)
        # return type.__new__(cls, clsname, bases, uppercase_attrs)
        return super(UpperAttrMetaclass, cls).__new__(
        	cls, clsname, bases, upptercase_attrs)
    
# 使用
class Item(metaclass=UpperAttrMetaclass):
    pass
  • __new__在实例类创建的时候调用