Re: Knotty puzzle with chaining to files not known at compile time

["Rory Hewitt" <roryhewitt@xxxxxxxxx>]

James,

One final solution:

If you're simply retrieving this data (i.e. you're not actually updating
it), you can do the following:

1. Define a 'generic' file as internally defined with no key and with a
record length as long as the longest possible record length of any of the
files you would access. It doesn't need any keys defined.

2. Define an array with each entry being a long string (as long as the
longest record length)

3. Define a set of dummy data-structures the same as the various possible
record layouts - defined as BASED if you're concerned about space)

4. Load the entire file into the array (first time round)

5. Use qsort() and bsearch() to get the record you want then overlay the
array element with the required data-structure.

Depending on the amount of work (CHAIN's, that is) you're doing, this might
even give better performance than other methods. It's pretty generic, so you
could add new file definitions as you see fit. Alternatively, you could
simply put it all in a nice neat procedure in a service program, where the
procedure is passed a file name and key and returns the array element as a
character string - that way, there's absolutely no hard-coding in the
procedure - you only need to define whichever of the record format
data-structures that you need in the calling program, e.g.

/free
  FileABCRecord = GetFileRecord( 'FileABC' : Key1 : Key2 : Key3 );
/end-free

I have LOTS of examples of this sort of thing in both RPG, fixed-fornmat
RPGLE and free-format RPGLE if you want.

Just a thought...

Rory