Re: SetLL *start

On 2/27/11 2:08 PM, M. Lazarus wrote:

Is there any good technical (not historical) reason that we still
have any opcodes that can't use record formats and file names, for
data files, interchangeably? PF's can't contain multiple formats.
Multi-format LF's are relatively rare nowadays. The only time it
would require differentiation is if a MFLF is used.

Is there a consideration to relax that requirement?

Just some thoughts which may or may not be relevant to that request, so FWiW...

Overrides of a database file to another file [with multiple formats], even to a device file may be an issue. The RPG language operates over the Common Data Management for accessing Database and Device files, versus defining the rules of data management. The record format is /common/ across the file types, and thus the RcdFmt is reflected in the Common Data Management interface to the database file, just as to the various device file types. Consider that DSPFD of a Save File [device file attribute SAVF] shows that the file has a format which is defined in the ODP even though no actual internal *FMT object type exists; if any extended type attribute of the *FILE object type had no use for a format, that is surely one, but for reading and writing, the common DM requires the format to be /common/ across the various file types.

The data management and database support multiple formats for a PF via "redirection" to an external format; I know only of IDDU in this capacity. I am not aware if there is any support via RPG for that capability; i.e. access to a program-described file as though the file were externally described, via redirection to the file and record format definitions in the IDDU [*DTADCT] data dictionary. To the common data management the difference between MFLF and MFPF is minor; i.e. they operate effectively the same, in how the request is handed off to the database, where both require a format name [though possibly defaulting to *FIRST if unspecified] to operate properly.

Some interfaces such as OPNQRYF offer a special value *ONLY for the RcdFmt such that a file being acted on, for which more than one format exists, an error will be issued; e.g. CPD3104 for the FILE parameter.

Regards, Chuck