Re: in & out parameters in RPGLE

[Craig Richards <craig@xxxxxxxxxxxxxxxx>]

Booth,

In case of it's of any interest - just to add to a point that Bradley
made...

Once you start getting used to using the return value, writing functions
which you can use in composition with other functions, you eventually end
up wrestling with the issue of = "how to I signal that something went
wrong?"

Sometimes people then revert back to having the return value as a boolean
to indicate success or failure, but that prevents you from using it
expressively.

The solution many people use is to implement some kind of throwError()
routine in a generic service program
This would send a meaningful escape message.
Then you can go back to using your return value for the real thing you want
to return.
You just wrap your procedure call in a monitor block and on-error retrieve
the previous error message and take appropriate action.

The first implementation I saw of this was from Greg Helton in 2005.

Here is a more recent link I found:

Throw and Catch <https://gist.github.com/greghelton/7493168>

regards,
Craig


On 17 September 2018 at 15:34, Justin Taylor <JUSTIN@xxxxxxxxxxxxx> wrote:

> I'm assuming the caller is also RPGLE (rather than something like a Db2
> stored procedure).
>
>
> By default parameters are read/write.  You can specify CONST or VALUE on
> your prototype to make them read-only.  The difference between CONST and
> VALUE being whether the local variable can be modified, but in either case
> the caller variable is not changed.
>
>
> You can only return a single return value (I often return a data structure
> when I need multiple values).  You declare the return type on the prototype:
>
> Dcl-pr myProcdure int(10);
>
> This will return an interger value.
>
>
> HTH
>
>
>
>
> ________________________________
> From: Booth Martin <booth@xxxxxxxxxxxx>
> Sent: Saturday, September 15, 2018 9:14 PM
> To: RPG programming on the IBM i / System i
> Subject: in & out parameters in RPGLE
>
> This seems straight forward but is it?  The RPG world has gone places I
> never imagined.
>
> I want to use PR/PI for the parameter(s) needed as input for a program,
> right?
>
> But what about the return parameter(s)?
>
>
>
>
>
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