Re: Models...

From: Magnus Lie Hetland <[email protected]>
> >>> proxy.attr = value
> >>> proxy.attr is value
> 1
>

OTOH personally I still find to require the idiom

proxy.modify(attr=newval)

to change the value/a model in-place without substituting it awkward.

IMO

proxy.attr = value should change a possible model in-place
OTOH proxy.attr should return the model or the value

and then a model would be installed with

proxy.installModel('attr',Model())

> But, as I said, I think it is better to require the Wrapper to make
> fewer assumptions about the values it receives; e.g. a coordinate will
> be number-like, but not necessarily an int. If the back-end needs an
> int, then the setter should be implemented something like:
>
>   def setX(self, x):
>       if self.widget is not None:
>           self.widget.x = int(x)
> (assuming that we keep the "wrapper is not None"-checking in the
> Wrapper).
>
> The more I think about it, the more I'm convinced that this is the way
> to do it.

the shorter and sweeter to write we can make the wrappers the better,
OTOH they should be copy-and-past-proof, and not too much things should
happen implicitly, so:

[assuming that Dallas saying Proxy manage models means that he has not adopted
passing settesr/getters along to models (?) ]

- having getters to assume that widget is set is OK, if this can be enforced,
because it makes sense in general and does not require special cases
- for setters to check explicitly for widget is sensible, because some need a
widget already there and some trigger widget creation so doing otherwise would
require some magic/implicitness

OTOH apart from implemetation issues at the higher levels, I don't see why it
is bad to assume/enforce that only values are passed to wrappers. I mean
expecting them to convert things is also sensible but makes wrapper code more
convoluted and does it increase clarity?

Unrelated:
*) We should check the issue with setX etc and setGeometry and wrapper
subclasses overriding only setGeometry

*) What is the general opinion about aggregates and models behavior?

Samuele.







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