[myhdl-list] MEP 107 - update assessment

[Jan D. <ja...@ja...>]

MEP 107 has been rewritten with support for attribute
lookup only - ok.

Comments:

1) the proposal is to support attribute lookup with an
arbitrary depth. Until now I had only considered a
single level of lookup.

I think support for arbitrary depth may complicate
things significantly, and I am not sure that there is
good use case that warrants the effort.

2) I miss lists of signals. I believe people will want
to use the container as a namespace for all signal-like
objects that are currently supported, including lists.
I expect this would not add too much additional
difficulties to implement.

3) I don't think the difference between class attributes
and instances attributes is subtle. I also think that
the overwhelming usage of the lookup feature will be
for instance attributes. In short: I would remove the
explication of the difference; I think it will only
confuse people without adding value.

We could restrict the examples to instance variables,
but add a note in the end that attribute lookup is
general (as I think it can be without too much problems).
This would include class attributes, but also lookup
in modules or in NamedTuples.

4) Currently, MyHDL supports only local variables (this
may change with Python 3.0 in the future) that do not
take part in hierarchy extraction. Therefore, the way
they are named in conversion should also be different
and local.

That having said, I have not thought about lookup
support for variables and it may prove to be very
different from signals.

I think the most "urgent" need is for signals,
to emulate interfaces. We could consider to
keep variable support for a future MEP, after we see
how the signal lookup support turns out.


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Jan Decaluwe - Resources bvba - http://www.jandecaluwe.com
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