Re: retrieving only specified fields ?

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On Thu, Jun 17, 2004 at 06:00:34PM +0300, raptor@xxxxxx.xxx wrote:
> if we have the setup u mentioned then i want to say :
> my @cd = CD->retrieve_all();
> to retrieve only fields "title, year" instead of all  "cdid, artist, title, year"

CD->columns(Primary => qw/cdid/);
CD->columns(Essential => qw/title year/);
CD->columns(Others => qw/artist/);

> And which column to retriewe should be dynamic f.e. pseudo code :
> my @cd = CD->retrieve_all(qw(title year));
> my @cd = CD->retrieve_all(qw(cdid artist));
> my @cd = CD->retrieve_all(qw(artist title));

I really can't see why you'd want that. But if you really do have a
compelling reason, then your best bet is to make a subclass for each
variation you'll want:

package CD::Weird;

use base 'CD';

CD::Weird->columns(Primary => qw/cdid/);
CD::Weird->columns(Essential => qw/title artist/);
CD::Weird->columns(Others => qw/year/);

You could conceivably mess with these in the one class at run time, but
in general that's a Very Bad Thing(tm).

Tony