Re: [myhdl-list] Signal getattr and setattr

[Christopher L. F. <chr...@gm...>]

Jan Decaluwe wrote:
> Chris:
> 
> I don't have a lot of time these days (moving to new house) but

No problem, this is not a bug often encountered and I have a work around 
for accessing the "contained" objects attributes/properties.  Enjoy 
moving to the new house!

> did your patch mean that __slots__ is the problem?

I don't believe __slots__ is the problem.  And you do get the 
performance increase from __slots__ but I don't know how much.

I believe the issue is how the copy works.  The copy tries to access 
variables before they exist?  I don't know the exact mechanism of the 
copy but that appears to be the issue.

By adding an attribute read in __init__ before it is set, a similar 
failure occurs.  Example first line of __init__ print self._val.

At this point two options would be remove __getattr__ or add __copy__ 
and __deepcopy__ to return a new instance and set attributes manually.

> 
> I would hesitate a lot to apply a patch that customizes __setattr__,
> and that makes every attribute access slower.

That is a good point, performance impact.  I do like the idea of a 
"transparent" Signal object but it is not looking to feasible.  But if 
the setattr isn't  propagated to the "contained" object does it make 
sense to allow __getattr__?


> 
> On the other hand, if __slots__ is the culprit, it would be one more
> argument to remove it. Explanations later.
> 
> (Removing __slots__ shouldn't change signal behavior, but may
> break some unit tests also.)
> 
> Jan
> 
> 
> 
> Christopher L. Felton wrote:
>> Ignore the patch that was previously sent for now!  I was careless and 
>> didn't run the regression tests.  After running the "tests" it exposed 
>> some issues.  It appears this method breaks the properties.
>>
>> Back to the drawing board.
>>
>> .chris
>>
>> Christopher L. Felton wrote:
>>> Attached is a patch with some modification to __getattr__ and adds the 
>>> __setattr__ in _Signal.py.
>>>
>>> I like the idea that the Signal class is "transparent".  Meaning that 
>>> the object that the Signal contains, its (the contained object) 
>>> attributes and properties can be accessed.
>>>
>>> The change checks the "slots" before accessing the "objects" (self._val) 
>>> attributes.
>>>
>>> The patch fixes the bug I previously posted, max recursion depth.
>>>
>>> I think I generated the bundle/patch correctly and tried to verify with 
>>> a separate repository clone.  The workspace I created the bundle from 
>>> has additional changes (mainly error/warning statements and prints) that 
>>> are not ready to be pushed.  The only changes should be the couple lines 
>>> in _Signal.py
>>>
>>> .chris
>>>
>>>
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>