[vhdl-200x] Closely related record types

All:

I finished the first cut for a closely-related record types proposal.  

http://www.eda-twiki.org/cgi-bin/view.cgi/P1076/RelatedRecords

There is one remaining item to be decided since there are several
possible rules for declaring two record types closely related.

1. Match record elements by name.
2. Match record elements by position.
3. Match record elements by name and position. 

Here is some arguments for/against copied from the TWiki page.

Rule 3 is the most restrictive and least ambiguous. In other words, it's
the safest. And it satisfies my current needs, so I'm content with it.
But it's also the most likely to not be useful in "obvious" cases.

Rule 2 is similar to the array rule. Array elements are converted by
position. But array indices don't usually convey information like record
element names. (The exceptions are the new fixed- and floating-point
packages, but they have to jump through some hoops to avoid issues with
VHDL's willingness to switch bounds and directions on array dimensions.)
Also, array elements are homogeneous while record elements typically are
not.

Rule 1 uses the element names, which typically represent the designer's
intent. However, naming is rarely unique (coming up with good names is
often hard), so variations are likely. This is my favorite option.

Opinions?  Feel free to edit the page or respond via email.  I'll try to
collect any good ideas from the reflector back to the proposal page.

---
Ryan Hinton
L-3 Communications / Communication Systems West
ryan.w.hinton@L-3com.com
 


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