Re: Am I playing with fire? (calling RPG subproc from CL)

[Scott Klement <midrange-l@xxxxxxxxxxxxxxxx>]

Hi Adam,

The really "unpredictable" results come from the caller not providing 
enough memory to hold the parameter.  As long as the caller provides 
parameters that are at LEAST as long as the RPG program expects them to 
be, you should not have to worry about unpredictable errors.

Of course, since CL doesn't really support the date data type, you do 
have to worry about "predictable" errors!  That is, if the CL program 
doesn't format the bytes correctly for the date field, then you'd get an 
"invalid date/time/timestamp" error on the RPG side -- but that's a 
predictable error.  The error message will clearly tell you what the 
problem is.

On the other hand, if the CL program passes too few parameters, or 
passes a variable that's shorter than the RPG program expects it to be, 
then the RPG program will start reading/writing into memory that the CL 
program didn't intend it to.  This is where the unpredictable results 
come from.  I can't even guess what sort of error you'd get!  It's 
unpredictable.

So... hopefully that makes sense.  Make sure the caller's variables are 
big enough, and enough parameters are passed, and they use the same 
passing convention (reference or value).

If the only problem is that they're different data types, then the 
errors will be "predictable" :)


AGlauser@xxxxxxxxxxxx wrote:
> I have an RPG procedure with the following prototype.
>      D utrmDates_newDateTime...
>      D                 PR             2  0
>      D  oldDate...
>      D                                 D   value
>      D  oldTime...
>      D                                6  0 value
>      D  unitsToAdd...
>      D                                9  0 value
>      D  unitTypeIn...
>      D                                7A   value
>      D  newDate...
>      D                                 D
>      D  newTime...
>      D                                6  0
> And my CL code:
> DCL        VAR(&startDate)      TYPE(*CHAR) LEN(10)
> DCL        VAR(&startTime)     TYPE(*DEC) LEN(6 0)
> DCL        VAR(&delayTime)  TYPE(*DEC) LEN(9 0)
> DCL        VAR(&delayUnits)  TYPE(*CHAR) LEN(7)
> DCL        VAR(&endDate)      TYPE(*CHAR) LEN(10)
> DCL        VAR(&endTime)     TYPE(*DEC) LEN(6 0)