RE: [htmltmpl] Sub-Classing HTML::Template v2.7

[Cory T. <Ct...@on...>]

Hello,

I have found the root of my problem!  All the code below was centered
around trying, and failing, to fully replace all instances of the
HTML::Template 'param( )' method within our code-base.  I thought that
by building a sub-class and overriding param, I would be able to
accomplish this.  However, I was unable to override all calls to 'param(
)' -- some within HTML::Template remained using the SUPER::param( ).

I attempted to overwrite the package method, as seen below.  This,
however, doesn't actually work.  So again, no dice.  Until I found the
following code in HTML::Template around Line #2112:

	$loop->[HTML::Template::LOOP::TEMPLATE_HASH]{$starts_at}

	  = HTML::Template->_new_from_loop(

This does not seem friendly to sub-classes ... I didn't see any
references to this type of issue in Damian Conway's Object Oriented Perl
book, but I found a solution that works great for my sub-classes.

	$loop->[HTML::Template::LOOP::TEMPLATE_HASH]{$starts_at}

	  = ref( $self )->_new_from_loop(

This way, the "_new_from_loop" call always occurs against the correct
class -- HTML::Template or otherwise.  I have no production code to test
compatibility with HTML::Template::Expr so I cannot state if this type
of change will work for everyone trying to sub-class HTML::Template.

However, I do know that making this change caused my sub-classes to
completely work and I am very happy about that.

Sincerely,
Cory Trese
Lead Web Application Developer
 
O'NEIL & ASSOCIATES, INC.
495 Byers Rd.
Miamisburg, Ohio 45342-3662
Phone: (937) 865-0846 ext. 3038
Fax: (937) 865-5858
E-mail: [ct...@on...]


|> -----Original Message-----
|> From: htm...@li... 
|> [mailto:htm...@li...] On 
|> Behalf Of Cory Trese
|> Sent: Thursday, March 03, 2005 11:32 AM
|> To: htm...@li...
|> Subject: [htmltmpl] Sub-Classing HTML::Template v2.7
|> 
|> Hello,
|> 
|> From some previous traffic on this list, Sam Tregar said:
|> 
|> |> Ultimately HTML::Template v2 doesn't offer much in terms 
|> of official 
|> |> support for sub-classes and extensions.  That's a 
|> deficiency I intend 
|> |> to address in the perpetually-delayed v3.
|>  
|> I am trying to create a sub-class of HTML::Template that 
|> over-rides the 'param( )' method.  The code below "works" -- 
|> mostly -- but I have a feeling that I'm doing this all 
|> wrong.  Does anyone have some advice or a link on 
|> HTML::Template v2 sub-classing?  I looked at 
|> "HTML::Template::Expr" -- my code below is based, roughly, 
|> on this module.
|> 
|> My major questions are:
|> 
|> 1. How does a sub-class of HTML::Template construct itself?  
|> Should I over-ride 'new( )' or use something like 'make_new( 
|> )' to wrap 'new( )'
|> or 'SUPER::new( )'.
|> 
|> 2. What packages should my 'param( )' method be overridden 
|> in?  More than HTML::Template?
|> 
|> The thing that doesn't work right:
|> 
|> 1. calls to 'param( )' seem to loose my 'i18n_strings' 
|> object -- it isn't ALWAYS present in 'options' when I call 
|> 'param( )', just most of the time.  
|> 
|> I _think_ that this is somehow related to some of the 
|> 'param( )' methods I'm using being in the class 'make_new( 
|> )' returns, and others, constructed somewhere else, but 
|> still using my 'param( )' method.  I know that's confusing I 
|> haven't slept much in the past few days, sorry.
|> 
|> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
|> package Service::Template;
|> 
|> use strict;
|> use vars qw($VERSION);
|> 
|> $VERSION = '0.01';
|> 
|> use HTML::Template;
|> 
|> use base 'HTML::Template';
|> 
|> sub make_new {
|>   my $pkg = shift;
|>   my $self;
|> 
|>   # check hashworthyness
|>   croak("Service::Template->new() called with odd number of 
|> option parameters - should be of the form option => value")
|>     if (@_ % 2);
|>   my %options = @_;
|> 
|> 
|>   # create an HTML::Template object, catch the results to keep error
|>   # message line-numbers helpful.
|>   eval {
|>     $self = $pkg->new(%options );
|>   };
|>   croak("Service::Template->new() : Error creating 
|> HTML::Template object
|> : $@") if $@;
|> 
|>     $self->{options}->{i18n_strings} = $options{'i18n_strings'};
|> 
|> 
|>   return $self;
|> }
|> 
|> 1;
|> 
|> package HTML::Template;
|> 
|> sub param {
|>  ...
|> }
|> 
|> 1;
|> 
|> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
|> 
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