Re: Prototypes and parameters

A few possible solutions:

    1) Use a return value instead of a parameter.  Of course, that would
        require you to use subprocedures instead of programs.

    2) Make the 2nd parameter be OPTIONS(*VARSIZE) of the maximum length,
        and add a 3rd parameter indicating the length of the variable.
        Then, make sure your "generic popup" program only touches as
        many bytes of the parameter as the number passed indicates.

        then you calling program would look like:

                  callp   lookup('TERMS': terms: %size(terms))

    3) do the same thing as #2, but instead of passing the length
         as a parm, calculate the length based on what the correct
         value would be for the data indicated by the first parameter.

    4) Use a varying field (but then all of the programs calling it
          would also need to use varying, which isn't ideal IMHO)

You mentioned OPDESC... I have very negative feelings towards OPDESC.
It works for me MOST of the time, but every so often a program using
OPDESC will suddenly not work because it can't find the operational
descriptor.  No rhyme or reason.  Not only that, but OPDESC creates more
complicated code than it's worth.


On Thu, 31 Oct 2002, Reeve Fritchman wrote:
>
> I have a general-purpose pop-up window used to display and select values
> from a reference file.
>
> Parameter 1 is the reference name and it's passed in as a literal ('TERMS',
> 'STATE').
> Parameter 2 is the field I want the value selected by the user returned into
> (back to the caller).
>
> Both parameters are 10A.
>
> Currently, the program is called with a prototype using EXTPGM(‘LOOKUP’).  A
> typical implementation looks like this:
>
>      C                   callp     lookup('TERMS':q_alpha_10)
>      C                   eval      terms_code =
> %subst(q_alpha_10:1:%size(terms_code))
>      C                   callp     lookup('STATE':q_alpha_10)
>      C                   eval      sh_state =
> %subst(q_alpha_10:1:%size(sh_state))
>
> Now, the complication: the size of the second parameter varies (based on
> what I’m looking up): "terms_code" is 3A, but "sh_state" is 2A.  Improper
> management of the parameters (size) has caused problems (decimal data errors
> because the improperly-sized parameter 2 overflows into adjacent fields in
> memory); the second line solved the problem.
>
> Because LOOKUP is called with EXTPGM, OPDESC doesn’t work.  Yes, it should
> be in a service program but circumstances of time and customer politics
> don't allow it.
>
> I’ve done this too:
>
>      C                   callp     lookup('TERMS':q_alpha_10)
>      C                   eval      terms_code = q_alpha_10
>      C                   callp     lookup('STATE':q_alpha_10)
>      C                   eval      sh_state   = q_alpha_10
>
> This is the ideal solution:
>
>      C                   callp     lookup('TERMS':terms_code)
>      C                   callp     lookup('STATE':sh_state)
>
>
> I've tinkered with VARYING, setting the length, etc. but am unable to come
> up with a way to
> implement the ideal solution.  Perhaps it’s too much Halloween candy, but
> I'm sure there's a better way to juggle OPTIONS(*VARSIZE) and VARYING to
> make this work...or is there?
>
> Thanks,
> rf