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<== Date ==> <== Thread ==>

Subject: Re: VDCT expand and template constructs
From: Kay-Uwe Kasemir <[email protected]>
To: Andrew Johnson <[email protected]>
Cc: "Rees, NP (Nick)" <[email protected]>, [email protected], "Shepherd, EL (Emma)" <[email protected]>, Igor Verstovsek <[email protected]>
Date: Sat, 17 Dec 2005 13:35:12 -0500

On Dec 16, 2005, at 17:59 , Andrew Johnson wrote:
these are subtly different. If a port macro is not resolved then it
shouldn't be an error, I believe it should be treated as if it never
existed in the first place.

I strongly disagree. If a parent diagram is trying to use information from a port that a template it's expanding doesn't actually define, then the parent diagram is wrong and this should cause an error at instantiation time.

I think the naming of these 'text' or 'port' macros isn't 100% clear.

When we compare this to circuit diagrams
or IC pinouts, there are 'input' and 'output' ports.

For example, an IC that offers a 4 bit addition circuit
might have inputs for the power, clock, 2 x 4 input bits,
and outputs for the 4 output bits and 'carry'.

You have to connect the input bits to make the IC
work in any useful way.
You probably also want to connect something to the
4 output bits, but the circuit would still work
if you ignore some outputs.
And in quite a few cases you'll completely ignore
the 'carry' output.

So in this view of 'input' and 'output' ports
of a circuit, I would understand why the 'port macros'
(= ouput ports) can remain open-ended,
while 'text macros' (=input ports) better be resolved.

-Kay


References:
VDCT expand and template constructs Rees, NP (Nick)
Re: VDCT expand and template constructs Andrew Johnson

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