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Re: Criteria for Specification Languages
At 22:44 2/28/96, Bill Frantz wrote:
>Ben Laurie was kind enough to start a list of specification languages. I
>would like to start a list (in no particular order) of criteria to use in
>evaluating them.
>
>(1) Ease of understanding (Assuming a knowledge of C)
>(2) Cost of learning (Assuming a knowledge of C)
>(3) Cost of tools (e.g. ASN.1 compilers) in both $$$ and bother.
>(4) Compactness of machine representation (these things are going to
> be sent over networks and stored in machines)
>(5) Adaquacy of expression (can it express what we need it to?)
>
>more?
Yes --
I assume you're restricting yourself to the job of specifying data structures
in a normal programming language (what I called DDL) -- not in the other
2 things ASN.1 tries to do [chalk-talk about structure content; encoding
of structures between machines].
A DDL needs to present the author of a structure with the cues he would
face in C or PASCAL -- so that he behaves as a programmer rather than as
a chalk-talk dreamer while defining a structure.
A DDL should not allow known dangerous things [e.g., C's cast, PASCAL's CASE,
C's UNION, FORTRAN EQUIVALENCE, ....].
I would leave your (4) as a separate problem -- to be handled by some
other mechanism which is devoted to packing, shipping and unpacking
structures in a way independent of endianness and word (pointer) width.
- Carl
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