Variable prototyped parameters. -Reply

David Morris

>>> "Jon Paris - jonp@vnet.ibm.com - AS/400 AD" <jonp@VNET.IBM.COM>
09/04 3:02 pm >>>

Why do you not know the data type? You say that the called routine knows
the type, so I'm a little confused as to why you can't simply code it in
the PR. All of this is a long winded way of saying that if you tell us
what you're trying to do we may be able to offer alternative suggestions.

We generate our database files from a set of files that describe the files. 
Keys, unique keys, candidate keys, attributes, etc.  I am currently designing a
set of standard functions to replace the chain, read, setll, open, etc. opcodes.
 Why?  To allow dynamic database changes (without recompilation), custom
opcodes, simplify database access, ensure data integrity, provide standard
trigger feedback, dynamic journaling, seamless SQL, etc.

This question arose while defining prototypes for procedures that will 
require a list of key values passed from an application.  During development,
testing, or when in debug, each procedure implements a routine that verifies
the passed and returned parameters.  In this routine we would like to be able
to type check that the key field attributes passed match the keys field
attributes of the file (which we know).  IE:  GetRcd(FileHandle:  *equal:
RtnFieldStruct: Key1: Key2: Key3).  I could pass the names of the keys in a
string like 'key1, key2, key3', but I would have to require that the return
structure be I/O and the keys be defined in the return structure.

The goal here is to catch errors while a program is still in development. 
When we implement this new interface it will be utilized in every application. 
A little work here could save many hundreds of hours down the road.  ILE is
enabling us to create very dynamic applications.  The compiler type checking
is great but a way to turn it off and perform this function at run time would
greatly enhance the flexibility of RPG.  We have coded around this situation
many times.  The difference here is that these procedures will be used in
hundreds of programs.

Thanks for your help


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