On Wed, Oct 31, 2001 at 08:03:36AM +0800, Gunther Birznieks wrote:
> Yes, this is another benefit of using a strategy pattern, it goes beyond
> simple directory traversal. Theoretically a given strategy driver could be
> written to search for templates inside databases according to a set of
> configure-time rules.
What, like subclassing Template::Provider to fetch templates from a
database? :-)
> Another useful pattern for these strategy drivers is chaining. So basically
> if it's not found in one strategy driver it might try a second one...eg
> attempt to find the schema in a DB but if it's not there, downgrade to file
> system.
What, like being able to define multiple template providers which are
chained together in precisely that way? :-)
> Anyway, the idea here in terms of having made the suggestion is that using
> this pattern would allow pluggable template search and loads which seems to
> me what people really want.
That's a very good idea! :-)
> Of course, the majority of people need a "simple" search pattern that
> exists now -- it's OK that this is the "default strategy" because you do
> not want to penalize the majority of user's whose needs may be simple. But
> the goal would be to make power user's capable of doing a lot of different
> search patterns.
Indeed. In case you hadn't got the message from the numerous smileys,
that's exactly how TT currently works. The Template::Provider module
implements the strategy fo finding and fetching templates. Chris Nandor
has indeed subclassed it to serve templates from a database for Slashdot.
So you can write your own Template::Provider module to implement any kind
of search algorithm. The LOAD_TEMPLATES option allows you to specify one
or more template providers to be search in turn, chain-of-command style.
my $provider = My::Provider->new(...);
my $template = Template->new( LOAD_TEMPLATES => $provider );
You can also give names to different providers to map particular template
request onto certain strategies:
my $template = Template->new(
LOAD_TEMPLATES => [ $regular, $search, $database, $http ],
PREFIX_MAP => {
find => 1,
dbase => 2,
http => 4,
}
);
Then you can do:
[% INCLUDE header %]
[% INCLUDE find:header %]
[% INCLUDE dbase:header %]
[% INCLUDE http://andywardley.com/templates/header %]
The PREFIX_MAP currently isn't documented because I'd like to clean up
some of the configuration details before I encourage too many people to
use it. But in principal, the functionality is there.
A
