Re: enhancements to H::T

At 01:40 PM 12/9/03 -0500, Sam Tregar wrote:
> On Tue, 9 Dec 2003, Mathew Robertson wrote:
>
> > - TMPL_ELSIF tag, eg <TMPL_ELSIF somevar>
>
> I've certainly had a lot of requests for this feature, but I'm still
> reluctant to include it.  I think it would only enable people to build
> even more complex logic into their templates, which is not generally a
> good idea.

Right now, people are attempting to code around the problem like this 
(somewhat contrived example):

<TMPL_IF foo>
    <p>foo is true</p>
<TMPL_ELSE>
    <TMPL_IF bar>
        <p>bar is true</p>
    <TMPL_ELSE>
        <TMPL_IF baz>
            <p>baz is true</p>
        </TMPL_IF>
    </TMPL_IF>
</TMPL_IF>

Whatever complexity might be added by TMPL_ELSIF, it must be better then this.


> > - support for custom tags, eg <TMPL_CATGETS ...>
>
> I'll be interested to see how you coded this.  I'm not sure the
> current code base can support this cleanly...  And even though I put
> it in my HTML::Template v3 design doc I'm still not sure it's a good
> idea.  (Go figure)
>
> > - trailing slash in tags, aka <TMPL... />
>
> This is trivially done in a filter, so there's no reason to add it to
> the core code.

Filters strike me as being one of those things in Perl that look easy, but 
often end up having subtle edge cases that will someday cause your computer 
to create Global Thermonuclear War, or something.  Having hooks in the 
parser (as stated in the v3 design) would be a very Good Thing, IMHO.


> > - TVPL_VAR support for HTML=TEXT which allows paragraphs of text to be 
> formatted to respect newlines
>
> This is easily done with HTML::Template::Expr and is too task-specific
> to go in the core code.  I've done this task a few times and each time
> I've done it a little differently (<br>&nbsp;<br> vs. <p>, wrapping
> long lines vs. no wrap, etc.).
>
> > - dot syntax, eg 'user.name'
>
> Allowing dots in variable names seems harmless enough.
<snip>


The thing is, 'user.name' isn't a variable name in the traditional 
way.  Rather, it's saying 'I want the attribute "name" for the variable 
"user"', thus providing a more OO approach.

I imagine that this would be implemented by passing an object that provides 
accessors for the fields that would show up in the template.  For the 
example above:

package My::UserVar;
use base 'HTML::Template::Var';  # For example

sub new
{
    my $class = shift;
    my $in = shift || { };
    return unless ref($in) eq 'HASH';
    my $self = { map { $_ => $in->{$_} || '' } qw( name addr city state 
postal )};
    bless $self, $class;
}
sub name { $_->{name} }
sub addr   { $_->{addr} }
sub city    { $_->{city} }
sub state  { $_->{state} }
sub postal { $_->{postal} }


package main;

# $tmpl defined elsewhere, holding an HTML::Template object
my $user = My::UserVar->new({ name => 'foo', addr => 'bar' });
$tmpl->param( user => $user );



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