[英]How to detect and trigger function when a class's __init__ variable is changed
我希望能够监视变量并在我的 class 内部有一个 function 在我的 class 的实例被更改时被调用。
class Example:
def __init__(self, content):
self.content = content
example1 = Example('testing')
example1.content = 'testing123'
我希望能够检查example1.content
是否已更改/更新,如果已更改,请运行一些代码。
这是你要找的吗?
class Example:
def __init__(self, content):
self.content = content
def __setattr__(self, name, value):
if name == 'content':
if not hasattr(self, 'content'):
print(f'constructor call with value: {value}')
else:
print(f'New value: {value}')
super().__setattr__(name, value)
if __name__ == '__main__':
example1 = Example('testing')
example1.content = 'testing123'
Output:
constructor call with value: testing
New value: testing123
您可以像这样在 class 中使用属性设置器:
class Example:
def __init__(self, content):
self.content = content
@property
def content(self):
return self._content
@content.setter
def content(self, value):
if hasattr(self, '_content'):
# do function call
print("new content! {}".format(value))
self._content = value
x = Example('thing')
x.content = 'newthing'
new content! newthing
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