Re: Pagers and Iterators

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On Fri, Feb 25, 2005 at 06:55:30AM -0500, Sean Davis wrote:
> 
> On Feb 25, 2005, at 6:47 AM, Simon Wistow wrote:
> 
> >	sub foo {
> >		my $self = shift;
> >		some_munging($self->actual_column);
> >	}
> >
> >
> >i.e the operation done in some_munging() cannot be done in SQL
> >
> 
> 
> It looks like the some_munging is done per-row?  If that is the case, 
> could you apply a trigger when you insert or update the table to 
> compute the value of some_munging(row) and store it in the database so 
> that you can later sort on it?

See my Class::MethodFilter for a way of doing this easily in (what I hope
is) a Class::DBI-ish way - e.g.

__PACKAGE__->add_method_filter('column', sub { .... } );

...

$obj->column_filtered;

If column_filtered does not exist, it'll calculate the value each time; if
column_filtered already exists (e.g. due to a ->columns call) the value is
calculated each time 'column' is updated and automatically stored.

If there's any way I could improve this to work better for the use cases
being discussed here, drop me a line or reply to list and I'll see about
adding it when I get time.

        -- 
            Matt S Trout            Brag sheet:    http://trout.me.uk/services.html
LAMP, Infrastructure        Contact:       services@xxxxx.xx.xx
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