Pascal News

.. /\ Qmnent CB1 Qmunents"
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1r¥iDt!.CA 92114
.Introc'k!ction
Jftlile working on our Pascal canpiler for the Intel 8086 (written in
U::SD Pascal), I have stulied closely several:of the User's Group software
tools with an eye toward converting them to that dialect. I have the
follJi\Wing obser¥ations to make regarding the. handling of COIIIIIeIlts by
thpse tools and upon'the definitiQll of a CQIIIIlent in the Draft Standard
proposal Ill.
,lSO Standarci QmunentForms
This table eIURerates the four forms of canment pennitted by the
Draft Standar~.
Starting
Ending
For1DS Delimiter Delimiter
1
t~tn '~lfl
2 n(,*,' It*)"
3 ·~tn It-*)"
4 "(It" tt'lt
Nate:Fonns 3& .4 are prohibited by our UCSD compiler.
UCSD. Pa~l toument .1iaJ!dlin8
The UCSDPascal compiler that we use (a IIlIlICh-modified version 1.5)
pennits Forms 1 & Z of COJIIIlents, with a most'usefUl twist: a comnent
be81;11l by a curly bracket can only be tenninated by a curley bracket, and
one beg1;1Il by the "C""digraph can only be tepninated by the n*) .. digraph.
Users whose Syst.WIS doo't .permit both forms are unaffected, but those of
us who have curley bracket characters are luci:ky. By using only form 1
for normal cClllllents. we are able ·to "canment: out"our temporarily delete
bo!iies of text (using form Z) ina natl.lral and error-free manner.
Draft Standard Suggestion
Since the above manner of comment handling is most useful to some of us •
relatively cheap to implement for all of us, and invisible to those whose
character sets don't permit it, I suggest that the Draft Standard, section
6.1.8 paragraphy 1, sentence 1 be rewritten as follows:
The constructs "''' • .... 1" and "("" ••• "")" shall be comnents if the "i"
or "(*" does not occur within a ·character-string. The constructs "\" •.• "*)"
and "("" ••• ':/" are expressly forbidden.
The note in section 6.11 should be deleted.
Software Tools Qmunentary
It is interesting that the software tools published in Pascal News
are not unifonn in their handling of conments.
XREF (4), written by Pascal's
inventor, and ID21D (21 follow the UCSD convention while PRETIYPRINf (6]
and REFERENCER( 3J follow the Draft Standard.
FORMATI'ER1. 7J doesn't recognize
curley brackets at all!
References:
1. A.Mdyrnan, et al. ISO DP/7185 -- A Draft Proposed Standard for the
Progranming Language Pascal.
Pascal News It 18 (May, 1980)
2. Andy Mickel. Recoding a Pascal Program using ID2ID.
Pascal News * 15 (September, 1979)
3. Sale, A.H.J. User Manual - Referencer.
Pascal News • 17 (March, 1980)
4. Wirth, N., et a1. Cross Referencer Generator for Pascal PrQgrams.
Pascal News * 17 (March, 1980)
5. Shillington & Ackland (ed)' UCSD (Mini-Micro Cornputa:).
Pascal Version 1. 5 (January, 1980)
Nate: This reference does not discuss the UCSD comment handling;
it is included for completeness only.
6. Heuras' & Ledgard. Pascal Prettyprinting Program.
Pascal News • 13 (December, 1978)
7. Condict, Marcus & Mickel. Pascal Program Formatter.
Pascal News • 13 (December, 1978)