Re: Pascal-Standard Question - Gpc

7 Jun 2002


      Please see below ...
Joe.
...
-----Original Message-----
From:	Frank Heckenbach [SMTP:frank@g-n-u.de]
Sent:	Thursday, June 06, 2002 12:29 PM
To:	gpc@gnu.de
Subject:	Re: Pascal-Standard Question
da Silva, Joe wrote:
...
I've been following this debate and wondering just what the ISO
standards
...
define. As you know, it's not easy reading through the standards and
finding obscure little details such as this.  <g>
However, I think section 6.13 of ISO-10206 indicates that a program can
indeed consist of multiple modules and can include one main program,
each of which is terminated by a "full stop" (aka. "period").
Yes, even in any order. This is rather difficult to handle, if a
program precedes a required module. A way to do it is to split the
source file and pass each part separately to the compiler. This
could be done transparently by a preprocessor, and serve as a (more
general) replacement for the current feature ...
[Joe da Silva]
Yes, odd isn't it?
Well, IMHO, if it's too difficult to handle sections
    (ie. program-components) in any order, it should
    be an acceptable implementation restriction to
    require that the main program is the last section
    (in the usual "define it before you use it" manner).
...
...
Also, regarding EOLN and EOF, section 6.7.6.5 indicates that "When
eoln(f) is activated, it shall be an error if ... eof(f) is true".
This means, in my words, that it's a runtime error to test EOLn when
the file is already at EOF. However, 6.4.3.6 says:
: The structure of the type denoted by text shall define an additional
: sequencetype whose values shall be designated lines. A line shall be a
: sequence cs~S(endofline), where cs is a sequence of components
possessing
: the chartype, and endofline shall represent a special componentvalue.
:
: [...]
:
: Every value t of the type denoted by text shall satisfy the following
two
: rules:
:
:   a) If t.M = Inspection, then t.L~t.R shall be a linesequence.
:
:   b) If t.M = Generation, then t.L~t.R shall be ls~cs, where ls is a
:      linesequence and cs is a sequence of components possessing the
:      chartype.
:
: NOTE --- 5 In rule b), cs may be considered, especially if it is
nonempty,
: to be a partial line that is being generated. Such a partial line cannot
: occur during inspection of a file. Also, cs does not correspond to t.R,
: since t.R is the empty sequence if t.M = Generation.
This indicates that it doesn't support partial lines at the end of
the file except during writing -- whether or not that's a good idea
is certainly arguable (I don't really think so) ...
[Joe da Silva]
Yes, the standards seem to consider that a text file
    must consist of lines and that therefore such a file is
    invalid (as a text file) if there isn't an EOLN before EOF.
    Of course, such a file can still be a "file of char", but
    this means the text file features of read() and write()
    are lost.
IMHO, the ability of a compiler to handle invalid
    situations in a more "user friendly" manner, does
    not truly detract from it's standards compliance,
    provided this does not affect how it handles valid
    situations, of course. I consider it a form of "error
    recovery". Therefore, I see nothing really wrong
    with a compiler simply returning TRUE for eoln()
    when eof() is TRUE.
...
Frank
-- 
Frank Heckenbach, frank@g-n-u.de, http://fjf.gnu.de/, 7977168E
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