🚀 go-pugleaf

In article <3290002@hpctdls.HP.COM>, rbk@hpctdls.HP.COM (Richard Katz) writes:
> 'if ( i := 10 )' will produce a syntax error in Pascal while
> 'if ( i =  10 )' will produce an assignment in C, usually not
> intended.  FORTRAN uses .EQ. to make sure that there is no mixup

In article <2567@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>This has nothing to do with :=/= versus =/==. This has to do with C being an
>expression-based language and Pascal being a statement-based language.

Certainly the Pascal *compiler* picks up the error because Pascal is
statement based, however the compiler is hardly ever called upon to flag
that error, because with :=/= programmers rarely *make* the error.

In 'C' the problem arises both because it is expression based, allowing the
"if (assignment-expression)" construct, *and* because the assignment
operator is an overworked symbol which in many programming languages *and
other environments* implies equality.

>... If you want to flame a language, try
>BASIC ("if a = b then a = c"... the first is a comparison, the second an
>assignment).

The interesting thing about this, contrary to the implication, is that it is
neither ambiguous nor prone to create undetected errors.  The multiple
meanings of "=" are nicely distinguishable by context, even though using the
same symbol for assignment and equality is dubious from a conceptual point
of view.

The =/== problem is not one of context dependancy nor of symbol over-use, it
is one of *lack* of context dependancy which is not necessarily a bad thing
in itself, and the "related" ambiguity of "=".

If you look at 'C' and its use of =/== in a totally introverted fashion,
then there *is* no problem.

It is only because of the use of "=" in the world outside 'C' (and not only
in the context of programming languages) that it becomes a problem in 'C'
that "=" in the context of "if" means assignment rather than equality.

-- 
Ray Dunn.                      |   UUCP: ..!philabs!micomvax!ray
Philips Electronics Ltd.       |   TEL : (514) 744-8200   Ext: 2347
600 Dr Frederik Philips Blvd   |   FAX : (514) 744-6455
St Laurent. Quebec.  H4M 2S9   |   TLX : 05-824090