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From: gaynor@topaz.RUTGERS.EDU (Silver)
Newsgroups: net.lang
Subject: Re: compound statements
Message-ID: <5312@topaz.RUTGERS.EDU>
Date: Thu, 10-Jul-86 20:14:44 EDT
Article-I.D.: topaz.5312
Posted: Thu Jul 10 20:14:44 1986
Date-Received: Sat, 12-Jul-86 03:08:36 EDT
References: <5303@topaz.RUTGERS.EDU> <2322@umcp-cs.UUCP>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 78

[ If there is a line-eater, give me a sign!! ]
[ See, I told you there was no li

In article <2322@umcp-cs.UUCP], mangoe@umcp-cs.UUCP (Charley Wingate) writes:
] Silver writes:
] [....]
] ] What gives rise to ambiguity is the null statement.  Consider a
] ] language that allows null statements, and an arbitrary statement as a
] ] (sub-)program body.  In the following, example, to which procedure
] ] would the 'writestring' be bound?
]
] ] ===== example =====
] ] # I consider the 'program' keyword to be unnecessary. #
] ] procedure example (output - text)
] ]
] ]   procedure this
] ]
] ]     procedure that
] ]
] ] # the code in question #
] ] writestring (output, "What procedure calls this statement?")
] ] ===================
] 
] ] Recall how Pascal resolves 'else' clause ambiguities.  Simply bind it
] ] to the nearest unclosed 'if-then' (not 'if-then-else') statement.
] ] That convention is applicable here.  If the definition of the language
] ] stated that a statement is bound to the nearest unclosed procedure,
] ] then no ambiguity results.  The 'writestring' statement is bound to
] ] 'that', a null-statement to 'this' and 'test'.
] 
] Well, ACCCKK PTHT.  What if you have TWO statements?  Which belongs to whom?
] 
] Program X(output);
] 
] Procedure Y; { Begin }
] 
]    Writeln("A");
] 
] { End; } { Begin }
] 
] Writeln ("b"); Y;
] 
] { End. }
] 
] Now, with all the begin-end constructs eliminated, how do you tell which
] statements belong to which procedure?
] 
] (Obviously, the "begins" are all superfluous.  The "ends" aren't, though.)
] 
] C. Wingate

It's not how do you tell which STATEMENTS belong to which procedure,
but which STATEMENT.  If you want to have more than one statement for
the body of your (sub-)program, there MUST be some form of grouping
(ie terminator, delimiters).  I think therein lies the source of your
confusion.  I am not proposing that the groupers be thrown out, only
excluded when they're not necessary and there's no loss in clarity.

So, in your example, Writeln("A") would be bound to Procedure Y,
Writeln ("b") to Program X, and the code after that would probably
then generate some 'end of program expected' error.  To bind both the
Writeln ("b") and the call to Y to Program X, they must be grouped
somehow (the second commented-out begin-end pair would do nicely).

[ This appears to have been intended to be Pascal, which uses the ]
[ single quote to delimit text constants.  Flame on you! :-)      ]

                         _   /|
                         \`o_O'
                           ( )   Aachk! Phft!   
                            U

Disclaimer: The opinions and/or information and/or code expressed
            here were generated by this characature, stolen from
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            adding ears.  So don't look to me for a disclaimer!

Silver  {...!topaz!gaynor}