Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!gatech!psuvax1!psuvm!cunyvm!byuvax!hallidayd
From: hallidayd@yvax.byu.edu
Newsgroups: comp.lang.fortran
Subject: Re: Is this a correct Fortran 88 subroutine?
Message-ID: <790hallidayd@yvax.byu.edu>
Date: 8 Sep 89 02:05:17 GMT
Lines: 33

Steve Correll (sjc@key.COM), as per your message (<1018@key.COM>) concerning
the legality of the construct

>        SUBROUTINE X(L)
>        LOGICAL L
>        IF: IF ( L ) THEN
>            ELSEIF              ! This is not an ELSEIF statement
>            ENDIF IF
>        END

in Fortran 8x --- the answer is YES in fixed form, where blanks are not
significant; NO in free form, where a blank would have to appear between the
ELSE and IF in the marked statement (even if the blank were inserted, the
statement would be no less confusing to the human reader).  See syntax rules
R802 to R806 (section 8.1.2.1, p. 8-2), along with the syntax rule, R801, for
block  (section 8.1, p. 8-1) which alows empty blocks.  This _may_ show a
``failing'' in the way the if-construct-name is alowed to be used in
Fortran 8x.  This construct is still unambiguous, by the syntax rules, since
an  else-if-stmt  must include `(scalar-logical-expr)THEN', which the above
does not, however, this is a confusing construct for the human reader.

The question is: if the syntax alows all legal constructs to be parsed
unambiguously, is it necessary for the syntax rules to exclude all constructs
which can be confusing to human readers, regardless of how contrived such
constructs may be?

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  / David Halliday                                                      \
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