Re: [myhdl-list] Block return values (myhdl.BlockError)

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

I have been thinking about this for about
a month now, without a good resolution,
and it is holding development back.

We need to resolve this urgently though,
because if we go forward with @block a
release has to made before GSoC. (May 23).

It is a style I didn't think about before,
but of course it is something you can do
with dynamic Python...

My thoughts:

In this style, the return values become
part of the block interface. If we want to
support this with @block, we need to
permit different (perhaps all) types
of return values, and reorder them
using the decorator.

This seems to become complicated, and
also defies the purpose of @block somewhat
(stricter type checking).

So: if we don't support this, are we
really going to miss something in the
future? The workaround is of course
to use only the argument list for
the block interface, and to do type-dependent
processing of ports outside the @block.

Also, an intermediate workaround may
be to pass an "interface object" as
an argument, and populate it with
Signal objects locally within the @block.

Feedback is more than welcome.

Jan


On 29/03/16 15:54, Jos Huisken wrote:
> Hi,
>
> Sometimes I'm using a block like this:
>
> def tb():
>      m, clk, rst = clkrst()
>      return m, clk, rst
>
> In which 'm' is the list of instantiator objects, and 'clk'/'rst' are
> Signals.
> So this way you can specify a block in general:
>
> def unit(inputports):
>      ...
>      return m, outputports
>
> Note that this could be a preferred way of design. It just happened that I
> created few such examples.
>
> With the new block decorator this is not allowed anymore, raising a
> myhdl.BlockError.
>
> I can imagine that also other return values may be wanted by users.
> Is this something which can be taken into account?
> Or: should 'block's really be constrained in returning just block or
> instantiator objects?
>
> Thanks,
> Jos
>
>
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