On 3 Dec., 11:30, Nick Craig-Wood <[EMAIL PROTECTED]> wrote:
> > cls = self.__class__
> > if attr_name in cls.data_attr_names:
>
> self.data_attr_names should do instead of cls.data_attr_names unless
> you are overriding it in the instance (which you don't appear to be).
Yeah, I know. I just like the cls notation for code readability
because it
tells you that it is a class attribute, which is not instance-
dependent.
That may be legacy from my Java past, where I used to do it that way.
I know perfectly well that self. would do it. i just find that
notation
a little misleading
> > I1, Q1, I2, Q2 = bytes_to_data(buf)
> > self.__dict__["I1"] = I1
> > self.__dict__["Q1"] = Q1
> > self.__dict__["I2"] = I2
> > self.__dict__["Q2"] = Q2
> > return self.__dict__[attr_name]
>
> I think you want setattr() here - __dict__ is an implemetation detail
> - classes with __slots__ for instance don't have a __dict__. I'd
> probably do this
Oh my, I did not know that. __slots__?? Something new I got to
understand.
But you are right. thanks!
>
> for k, v in zip(("I1", "Q1", "I2", "Q2"),
> bytes_to_data(buf)):
> setattr(self, k, v)
> return object.__getattr__(self, attr_name)
>
And perhaps even more readable (how I do it now, no need to call
__getattr__ for an attribute, whcih is already there):
...
for attr, value in zip(cls.data_attr_names,
bytes_to_data(buf)):
setattr(self, attr, value)
return getattr(self, attr_name)
> :-)
>
> I would probably factor out the contents of the if statement into a
> seperate method, but that is a matter of taste!
Agreed. I thought about that myself for better code readability.
As a final comment, I have actually refacted the code quite a bit
as I have to do this ...OnDemand trick for several classes, which have
different data attributes with different names.
In this process I have actaully managed to isolate all the ...OnDemand
stuff
in an abstract PayloadOnDemand class
I can now use this "decorator-like"/helper class to very easily make
an ...OnDemand
variant of a class by just doing multiple inheritance - no
implementation:
class PayloadBaconAndEggsOnDemand(PayloadOnDemand,
PayloadBaconAndEggs): pass
I guess this somewhat resembles the decorator approach - I just could
not figure out
how to kake a general purpose decorator.
For this to actually work the "instant" PayloadBaconAndEggs class
simply has to define
and implement a few class attributes and static utility functions for
the unpacking.
-- Slaunger
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