Re: [htmltmpl] enhancements to H::T

[Joel <htm...@jo...>]

>At 05:55 PM 12/10/03 +1100, Mathew Robertson wrote:
>>
>>In a template you may do something like:
>>
>><TMPL_IF user>
>>     <TMPL_IF user.name>
>>        <TMPL_VAR user.name.first> <TMPL_VAR user.name.last>
>>     </TMPL_IF>
>>     <TMPL_IF user.address>
>>         <TMPL_VAR user.address.street>
>>         <TMPL_VAR user.address.town>
>>     </TMPL_IF>
>></TMPL_IF>
>>
>>
>>Normally your code would look something like:
>>
>>if (length $user->name->first or $user->name->last ) {
>>    $tmpl->param ('user' => 1);
>>    $tmpl->param ('user.name' => 1);
>>    $tmpl->param ('user.name.first' => $user->name->first );
>>    $tmpl->param ('user.name.last' => $user->name->last );
>>}
>>if (length $user->address->street or $user->address->town) {
>>    $tmpl->param ('user' => 1);
>>    $tmpl->param ('user.address' => 1);
>>    $tmpl->param ('user.address.street' => $user->address->street);
>>    $tmpl->param ('user.address.town' => $user->address->town);
>>}
>>
>>
>>With the 'structure_vars' support you can do this:
>>
>>$tmpl->param( 'user.name.first' = $user->name->first );
>>$tmpl->param( 'user.name.last' = $user->name->last );
>>$tmpl->param( 'user.address.street' = $user->address->street );
>>$tmpl->param( 'user.address.town' = $user->address->town );
>
>Actually, you'd just do this:
>
>$tmpl->param( user => $user );
>
>And H::T would take care of calling the necessary methods for you.

This is an easy workaround with a lovely little recursive function to traverse
your hashref structure. (This is a real example, try it for yourself. Although
I admit that one line of it is questionable, but it needs to know if a
reference is a scalar or a hash, otherwise errors abound.)

test.pl -- The code
-------------------
#!/usr/bin/perl -w
use strict;
use HTML::Template;

my $user = {name => {first => 'John', 
                     last => 'Doe'}, 
            address => {street => '123 Main St', 
                        city => 'Washington', 
                        state => 'DC'}};

my $tmpl = HTML::Template->new(filename => 'test.txt', die_on_bad_params => 0);
$tmpl->param(user => 1);
&populate($tmpl, $user, 'user');
print $tmpl->output();
1;

sub populate {
    my $tmpl = shift;
    my $struct = shift;
    my $curr = shift;

    foreach (keys %$struct) {
        $tmpl->param("$curr.$_" => 1);
        if ($struct->{$_} =~ 'HASH') {
            &populate($tmpl, $struct->{$_}, "$curr.$_");
        } else {
            $tmpl->param("$curr.$_" => $struct->{$_});
        }
    }
}   


test.txt -- The Template
------------------------
<TMPL_IF user>
  <TMPL_IF user.name>
    FName: <TMPL_VAR user.name.first>
    Lname: <TMPL_VAR user.name.last>
  </TMPL_IF>
  <TMPL_IF user.address>
    Street: <TMPL_VAR user.address.street>
    City: <TMPL_VAR user.address.city>
    State: <TMPL_VAR user.address.state>
  </TMPL_IF>
</TMPL_IF>

And if I remember correctly, Perl would allow you to "add" your own function to
do this in HTML::Template at runtime. Example:

    sub HTML::Template::foo {
        return "foobar\n";
    }
    
    my $template = HTML::Template->new(filename => 'blah');
    print $template->foo;

So technically, you could add a new function HTML::Template::structure_param
that would do all the ugliness when called with: (assuming $user is a hashref)

    $tmpl->structure_param(user => $user);
    
I love Perl.

--Joel