[Tutor] automatic setting of class property when another one changes

[Steven D'Aprano]

On Thu, Sep 15, 2016 at 12:30:34PM +0200, ingo wrote:

> Rather stuck with this one, I'd like to automatically (re)set the 
> propery "relaystate" when one of the others (Tm, Tset, Th) is set, 
> regardless of wether their value has changed.

The obvious way is to make Tm, etc properties, and have their setter 
method reset the relaystate property. Since they relay state cannot be 
calculated during __init__ until all of the properties have been set, 
simply bypass the properties in the __init__. See below.


> My code so far:

Thanks for showing your code, but you shouldn't drown us in masses of 
irrelevant code that has nothing to do with your problem. We don't care 
about the logging code you show. Take it out. In fact, the best way to 
demo code is to cut it down to the barest minimum demonstrating the 
problem:


class Thermostat(object):
    def __init__(self, Tm):
        self._Tm = Tm
        self.reset_relay()

    @property
    def Tm(self):
        return self._Tm
    @Tm.setter
    def Tm(self, value):
        self.reset_relay()
        self._Tm = value

    def reset_relay():
        self.relaystate = None


About a dozen lines, versus seventy for your code.

See also this for more information:
http://sscce.org/


-- 
Steve