Re: Pagers and Iterators

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Simon Wistow wrote:

>On Fri, Feb 25, 2005 at 03:37:56PM +0000, Simon Wistow said:
>  
>
>>Instantiating my own Iterator looks like the righthing to do.
>>    
>>
>
>and lo! it was - much easier than I thought as well :/
>
>Formatted for 72 cols - here it is for posterity.
>
>	
>my $pager = __PACKAGE__->do_pager($r);
>$r->{template_args}{items} = [ $pager->get_sorted_items ];
>
>#
># ... call template here
>#
>
>
>sub do_pager {
>    my ($self, $r) = @_;
>    if ( my $rows = $r->config->{rows_per_page}) {
>        return $r->{template_args}{pager} = 
>          $self->pager($rows, $r->query->{page});
>    } else { 
>		return $self 
>	}
>}
>
>sub get_sorted_items {
>    my $self = shift;
>    my @stuff = sort { 
>                       lc($a->get_price) 
>                       cmp 
>					   lc($b->get_price 
>                     }  $self->retrieve_all;
>
>    return Class::DBI::Iterator->new('Email::Store::Entity', 
>                                      \@stuff );
>}
>
>  
>
I imagine your get_price() function is expensive, if it's make a call to 
a web service, and you probably want to do that the minimum times 
necessary - that is, once per object, not twice per comparison inside sort.

Consider using the Schwartzian Transform, invented by Randal Schwartz 
and illustrated in this article:

    http://www.stonehenge.com/merlyn/UnixReview/col06.html

-ofer