Re: C style assignment of variable values

["Eric N. Wilson" <doulos1@xxxxxxxx>]

True, I had not thought about the difference between equality and
assignment... That would make things a little sticky! Then we surely would
have another V4Rx Gotcha thread that would go on forever :-)

I do like that alternitive that you listed. it's either that or make a
different assignment ( := ) or equality operator ( == ) a path I am sure no
one wants to go down.

The increment (++), decrement(--), and the other associated operators (*=,
+=, -=, /=)  would be cool as someone else pointed out.

Thanks again
Eric

______________________________________________
Eric N. Wilson
President
Doulos Software & Computer Services
2913 N Alder St
Tacoma WA 98407


----- Original Message -----
From: <boldt@ca.ibm.com>
To: <RPG400-L@midrange.com>
Sent: Tuesday, October 05, 1999 12:58 PM
Subject: Re: C style assignment of variable values


>
>
>
> Eric wrote:
> >Would it be possible to make the following expression valid in future
> >versions of the compiler???
> >
> >EVAL    C_NumRecs = C_MailFlags = C_UserFlags = 0
> >
> >And no I do not need to put a statement terminator on the end of that :-)
> >
> >It seems that evaluation of this sort of expression should be easy when
> >evaluated from right to left (like C does). Not a big thing but I like to
do
> >that sort of thing to reduce initializations to a small block of code.
And
> >yes I know that there are a million and one ways to achieve the same
goal,
> >Named datastructure with initializations etc... I just find the above to
be
> >readable and love to know what I am initializing near the code that I am
> >working with.
>
> Unfortunately, the = operator is overloaded in RPG IV.  It's used
> for both assignment and comparison.  The above EVAL statement is
> almost valid today.  Replace it with, say:
>
> EVAL    A = B = C
>
> and you'd have a valid RPG IV statement.  It wouldn't do what you
> expected, though.  First, expression B = C would be evaluated
> giving an indicator value.  The result of that comparison would
> then be assigned to A.
>
> The main issue here is that in RPG IV, assignment is considered a
> statement.  But in other languages, like C and Perl, it is an
> expression.  With assignment as an expression, you run into such
> messy issues like order of evaluation and side effects.  (Not to
> mention the common C bug: if(a=b)!)
>
> OTOH, we could possibly come up with some different syntax like:
>
> EVAL    A, B, C = 0
>
> Cheers!  Hans
>
> Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
>
>
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