Re: RPG IV program - comments requested

[Paul Tuohy <tuohyp@xxxxxxx>]

Peter,

Just to clarify:-

The procedure interface is the equivalent of the *ENTRY PLIST with the addition
that the compiler will validate it. The validation is performed by comparing the
definition of the procedure interface (PI) against the definition in the
prototype (PR).

On the same basis, in a calling module the compiler will validate the call
statement (CALLP or EVAL) against the definition in the prototype. Hence, since
the prototype will be required in many modules (each calling module and the
module in which the called procedure exists) it is best to have only one copy of
it and include it where required, using /COPY.

The reason that the compiler does not look at the called program is that the
called program may not yet exist. The validation is performed on the CRTRPGMOD.

I amn't quite sure that the version of the /COPY is an issue. If you are using
the wrong version, the module will not be created.

Paul Tuohy

Peter Dow wrote:

> Thanks David. But why does the one program that has the procedure interface
> also need the prototype? In fact, why call it two different things at all?
> My first thought when I saw all that was why doesn't the compiler simply
> look at the called program to determine the prototype (after all, I don't
> have to have a prototype for a BIF, and I'd prefer some sort of external
> definition) but I suppose it keeps the compiler simpler and helps the
> programmer to see it documented.
>
> A problem with using /COPY's to define prototypes is that there is no
> reference in the program indicating which version of the /COPY was used when
> the program was compiled. Which is one of the nice things about
> externally-defined files.
>

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