Re: Advantages of RPG

the thing that I have seen with other languages concerning SWITCH(or
select)
tons of frigging IF statements to set a variable just so i can
switch (e) {
case 0: docrap1();
case 1: docrap2();
}

why the heck go through 500 nested IFs just to see what to do via a
switch? while you're in the 500 nested IFs just docrap1() there instead
of adding more code that essentially does nothing but reiterate what
you've just determined? in RPG you can do BOTH the actual selection
criteria avoiding the 500 nested IFs and execute based on the
criteria...JMO
Thanks,
Tommy Holden



From:
Doug Palme <DPalme@xxxxxxxxxxx>
To:
RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>
Date:
06/23/2008 11:39 AM
Subject:
Re: Advantages of RPG



Could one also use a function / procedure such as:

Select;
When MyFunction() = 1;
Exsr Exitprocess;
EndSL;

which I believe would also work with either VB or C.......then again I do
not recall ever having tested that......

Again, I am not disagreeing with you.....just making an observation :)





From:
Joe Pluta <joepluta@xxxxxxxxxxxxxxxxx>
To:
RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>
Date:
06/23/2008 11:30 AM
Subject:
Re: Advantages of RPG



Doug Palme wrote:

your statement of "perhaps the best
implementation ever..." are you referring to the SELECT statement
specifically or the group as a whole? The reason I ask is that
SELECT-ENDSL is the same as SELECT CASE-END SELECT is it not?

If I am off the mark on this, please feel free to correct me.

Not a correction so much as a clarification. Most implementation of
CASE logic have actually been variations on the SWITCH statement. The
concept of a switch is that you have a single variable, and then you
execute logic based on the contents of that variable.

switch (a) {
case 1: doSomething1();
break;
case 2: doSomething2();
break;
default;
doSomethingElse();
}

SELECT on the other hand was much more a derivation of the old CASE
construct in RPG, where you could compare any two variables. And in
RPG, a combination of SELECT and procedures is incredible:

SELECT;

// Opcodes 01 and 02 don't need authorization
WHEN OPCODE = '01';
DoOpcode1();
WHEN OPCODE = '02';
DoOpcode1();

// Opcode 10 needs authorization
WHEN not Authorized();
SendError('Not Authorized');
WHEN OPCODE = '10';
DoOpcode10();

// Bad opcode
OTHER;
SendError('Bad Opcode');
ENDSL;

The code above is just stunningly simple for client/server programming.
I used this all throughout the RSDC Scheduler application and I was able
to create new servers in minutes. The fact that the WHEN can be as
complex as you need it, or even execute a subprocedure (which in turn
could call another program!) makes this one of the very best opcodes
ever designed for procedural logic.

Joe