Re: Stopping processing with using a bunch of if statements

Anyone who's coded in C has been bit by a missing "break" statement in a switch() structure. RPG SELECT doesn't have that problem - thankfully.

For the control that Rich wants, I would suggest an FSM driver routine. You can have very good control of what you want your program to do. Very easy to implement with a SELECT construct - but, apparently, Rich doesn't care for those.

Roger Harman
COMMON Certified Application Developer - ILE RPG on IBM i on Power



-----Original Message-----
From: RPG400-L<rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Vern Hamberg via RPG400-L
Sent: Monday, February 19, 2024 8:37 PM
To: rpg400-l@xxxxxxxxxxxxxxxxxx
Cc: Vern Hamberg<vhamberg@xxxxxxxxxxxxxxx>
Subject: Re: Stopping processing with using a bunch of if statements

Hi Rich

I was looking at SELECT-WHEN today, wondering if I remembered how it
worked. The point is this clause in the documentation - (only one WHENxx
is executed) - I believe this is different from how it works in C/C++ in
the switch-case statement - there you have to put a break statement
before the next case, otherwise it can process multiple cases.

So bottom line, only 1 matching WHEN block will be processed, then
control passes to the statement after the ENDSL. If no matching WHEN and
there is an OTHER block, control passes to the first statement after the
OTHER statement, otherwise it passes to the first statement after the ENDSL.

There shall be only one!

Cheers
Vern

On 2/19/2024 7:43 PM, Rich Marion wrote:

But, this is not the same as a bunch of "if" statements.
Select When clauses replace a bunch of "ELSEIF" statements, not "If"s. (I
think)

IMHO,

If statements are easier to read. You know exactly how they perform and
they give you complete control.
When I see a when clause, I always ask myself, "does it only execute the
first when that matches, or any when that matches". What if a When clause
further down is true? Will it execute too? Do I want it to?

At 2 AM in the morning, I do not what to have to have that thought.
IF is 2 characters of typing, WHEN is twice that.

When I see series of "If" statements, I know exactly how and what will
execute, even when I am half asleep.

But then, I come from the S34 days of the '70s with RPGII and indicators,
so I am old fashioned.


Rich



-----Original Message-----
From: RPG400-L<rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Chris
Pando
Sent: Monday, February 19, 2024 2:33 PM
To: RPG programming on IBM i<rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: Stopping processing with using a bunch of if statements

If the procedure returns an *On if in error.

Select;
When ( procedure1() );
When ( procedure2() );
When ( procedure3() );
.
.
.
EndSl;

The procedures will execute until one returns an *On

Chris Pando
chris@xxxxxxxxx
http://www.brilligware.com/

On Wed, Feb 14, 2024, 4:10 PM<smith5646midrange@xxxxxxxxx> wrote:

I have an RPGLE program that calls a number of procedures. If it is
in a procedure and it detects an error, I want it to stop processing
and exit back to the main procedure where the initial screen is
displayed to inform the user of the error. I do not want the program
to abend. Is there a way do to this without placing an if statement
after each procedure? That could get really ugly and it would
probably be easy to miss one because not all procedures can encounter
an error.



Here is an example.



Errorfound is an indicator type variable.



Begin Main;

Display screen for input;

Procedure1();

Display screen showing results of processing;

End Main;



Begin Procedure1

Procedure2();

If Errorfound;

return;

endif;

Procedure3();

If Errorfound;

return;

endif;

Procedure4();

If Errorfound;

return;

endif;

.more code

End Procedure1;



Begin Procedure2;

Whatever code is needed

If an error is encountered.

Errorfound = *on;

Return;

Endif;

End Procedure2;



Begin Procedure3;

Whatever code is needed

If an error is encountered.

Errorfound = *on;

Return;

Endif;

End Procedure3;



Begin Procedure4;

Whatever code is needed

If an error is encountered.

Errorfound = *on;

Return;

Endif;

End Procedure4;



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