将实例附加到列表时，属性设置器中没有 output

Question

I was just experimenting with the property decorators when I figured out that a print statement from within a property setter would not always do its job, all other conditions equal. In the below example, I am getting the expected output from the directly initialized class instance (the fiver section), but not when appending instances to a list (the objlist section). Python 3.5.3

class Celsius:
    def __init__(self,temperature=0):
        self._temperature=temperature
    
    @property
    def temperature(self):
        print("Getting value...")
        return self._temperature
    @temperature.setter
    def temperature(self, value):
        print("Guess, you know what you're doing...")
        if value < -273:
            print ("Impossible temperature...")
            self._temperature = -273
        else:
            self._temperature = value        

objlist=[]
objlist.append(Celsius(4))
objlist.append(Celsius(-499))

fiver=Celsius(5)
print (fiver.temperature)
fiver.temperature=-408
print (fiver.temperature)

Answer 1

In your __init__ you set the "internal" value _temperature directly. This doesn't call the setter , as the property.setter is defined over temperature .

If you want the __init__ to pass through the setter validation as well, funny as it sounds, just use the setter :

def __init__(self,temperature=0):
    self.temperature = temperature