Re: Open Access RPG question - how to tell which file a handler call relates to?

[Vern Hamberg <vhamberg@xxxxxxxxxxx>]

Peter

Have you actually run this and does it give you the results you expect? 
That is, that externalFile is the same in both cases? I ask because you 
mention a potential problem but did not explicitly say you'd tried it.

But it's an interesting problem - certainly the RPG native stuff knows 
what to do with things, what we are passed should be enough.

Vern

On 1/5/2011 7:03 AM, Peter Clifford wrote:
> We're trying to write a generic Open Access RPG handler which will process
> Excel files. We started this a few months ago, then get side-tracked and had
> to put it down, but are now returning to it.
>
> We're trying to work out how to tell which file in the calling program a
> particular handler call relates to, with absolute certainty, and think
> there's a potential (though unlikely) situation where that is not possible
> (unless we're missing something).
>
> Assume F-specs something like these:
>
> FXL_Intfce1IF   E             DISK    HANDLER('XL_HANDLER':XL_UserArea)
> F                                     USROPN
> F                                     RENAME(XL_IntFceR:IntfceR1)
> F                                     PREFIX(i1)
>
> FXL_Intfce2IF   E             DISK    HANDLER('XL_HANDLER':XL_UserArea)
> F                                     USROPN
> F                                     RENAME(XL_IntFceR:IntfceR2)
> F                                     PREFIX(i2)
> F                                     EXTFILE('XLINTFCE1')
>
> Then assume that at compile time, XL_INTFCE2 was overridden to XL_INTFCE1.
>
> The same handler is being used for both files. When the handler receives a
> call relating to an IO operation on either of these two files, so far as we
> can see the information provided does not allow us to distinguish between
> them: the external file is set to XL_INTFCE1 in both cases, as is the
> compiled-against file name.
>
> I acknowledge that this is not likely to be a problem 99.9999% of the time,
> but wouldn't things be much clearer, and probably more efficient, if the
> handler were passed some kind of file identifier, e.g. an integer denoting
> the particular F-spec being processed? We cant even see that the name of the
> file as used in the RPG program is passed. What we get are the name of the
> actual file to be used (externalFile) and the file compiled against
> (compileFile).
>
> We plan to store a set of internal file handles for processing the various
> files, but at the moment can't see how we can be completely sure which
> handle to select. As it stands, we think the best we can do is use either
> the externalFile details or the compileFile details or maybe a combination
> of the two.
>
> I'm hoping Barbara or someone can offer some advice here.
>
> Pete