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HTML::Template macros

by blokhead (Monsignor)
on Dec 04, 2003 at 23:17 UTC ( #312367=snippet: print w/ replies, xml ) Need Help??

Description: With the loop_context_vars switch in HTML::Template you can make some useful macros. I found myself needing things like this all too often:
$tmpl->param( foos => \@foo, num_foos => scalar @foo, bars => \@bar, num_bars => scalar @bar, ... );
So I made a macro that handles this inside the template by adding a <TMPL_NUM foo> directive. Does anyone else have useful HTML::Template tricks up their sleeves?

By the way, I'm well aware that this is a great example of the serious limits of templating using HTML::Template's philosophy. This is some ugly template-ese under the hood. This is why I will probably switch over to Template::Toolkit in the not-so-distant future (at least for projects where I'm the one writing the template).

use HTML::Template;

sub tmpl_num_filter {
    s[<TMPL_NUM (\w+)>]
     [<TMPL_IF $1><TMPL_LOOP $1><TMPL_IF __LAST__><TMPL_VAR __COUNTER_
+_></TMPL_IF></TMPL_LOOP><TMPL_ELSE>0</TMPL_IF>]g
        for ${+shift};
}

my $tmpl = HTML::Template->new(
               scalarref         => \do { local $/; <DATA> },
               filter            => \&tmpl_num_filter,
               die_on_bad_params => 0,
               loop_context_vars => 1
           );

$tmpl->param(hobbits => [
    { name => "Frodo" },
    { name => "Samwise" },
    { name => "Meriadoc" }
]);
print $tmpl->output;

__DATA__
These are my <TMPL_NUM hobbits> favorite hobbits:
<ul><TMPL_LOOP hobbits>
  <li><TMPL_VAR name>
</TMPL_LOOP></ul>

Comment on HTML::Template macros
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Re: HTML::Template macros
by jZed (Prior) on Dec 04, 2003 at 23:41 UTC

    I like to use simpler tags for variables in templates so I use the filter to turn %~foo~% into <TMPL_VAR NAME="foo"> like so:

    use HTML::Template; my $tmpl = HTML::Template->new( scalarref => \do { local $/; <DATA> }, die_on_bad_params => 0, loop_context_vars => 1, filter => sub { my $s=shift; $$s=~s/%~([^~]+)~%/<TMPL_VAR NAME="$1">/g; }, ); $tmpl->param( userid => 99999 ); $tmpl->param( username => 'foo' ); print $tmpl->output; __DATA__ <a href="%~userid~%">%~username~%</a> is easier to edit than <a href="<TMPL_VAR NAME="userid">"><TMPL_VAR NAME="username"></a>
    The heck with patents, here's how to protect your thoughts: <tinfoil>.o0(Martians can't read this)</tinfoil>
Re: HTML::Template macros
by jZed (Prior) on Dec 05, 2003 at 00:02 UTC
    Here's a hack to set the value of variables directly in a template itself.
    use HTML::Template; my $tmpl = HTML::Template->new( scalarref => \do { local $/; <DATA> }, die_on_bad_params => 0, loop_context_vars => 1, filter => sub { my $s=shift; $$s=~s/%~([^~]+)~%/<TMPL_VAR NAME="$1">/g; }, ); for my $key($tmpl->param) { next unless $key =~ /^SET_VAR_([^_]+)_(.+)$/i; $tmpl->param($1=>$2); } print $tmpl->output; __DATA__ %~SET_VAR_p1_http://somelong.net/path~% %~SET_VAR_p2_http://someother.net/otherpath~% %~p1~%/foo.html %~p1~%/bar.html %~p2~%/baz.html %~p2~%/qux.html
Re: HTML::Template macros
by jeffa (Chancellor) on Dec 05, 2003 at 04:14 UTC
    ++blokhead, but if you find yourself needing more of those "things", you might want to look into Template. Now don't get me wrong, i love HTML::Template, but sometimes i like having more expressional power, and Template has it:
    These are my [% hobbits.size %] favorite hobbits: <ul> [% FOREACH hobbit = hobbits %] <li>[% hobbit.name %]</li> [% END %] </ul>
    Another cool thing (possibly overkill) is that each hobbit could be a real object, not just a hash in a list.

    Oh yeah, you can get rid of the file slurp in your code by using the filehandle attribute instead of the scalarref one:

    filehandle => \*DATA,
    Much nicer and more efficient. Cheers. :)

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
    -R--R-RR-R--R-RR-R--R-RR
    B--B--B--B--B--B--B--B--
    H---H---H---H---H---H---
    (the triplet paradiddle with high-hat)
    
      Much nicer and more efficient. Cheers. :)
      It's just as efficient, but not more efficient (look before you speak ) :D
Re: HTML::Template macros
by thraxil (Prior) on Dec 05, 2003 at 04:51 UTC

    for populating <select>'s i use this sub:

    sub selectify { my $values = shift; my $labels = shift; my $selected = shift; my %selected = map {$_ => 1} @{$selected}; return [map { { value => $_, label => shift @{$labels}, selected => $selected{$_} || "", } } @{$values}]; }

    you use it in a script like:

    $template->param(foo_loop => selectify(\@values,\@labels,\@selected));

    and a template file like:

    <select name="foo"> <tmpl_loop name="foo_loop"> <option value="<tmpl_var name="value">"<tmpl_if name="selected"> sel +ected="selected"></tmpl_if>> <tmpl_var name="label"> </option> </tmpl_loop> </select>

    i usually have the stuff inside the <tmpl_loop> factored out into its own file so i can just do a <tmpl_include> anytime i have a select list. ie, this is what i you actually see all through my templates:

    <select name="foo"> <tmpl_loop name="foo_loop"> <tmpl_include name="option.tmpl"> </tmpl_loop> </select>

    update: fixed some unescaped entities.

Re: HTML::Template macros
by samtregar (Abbot) on Dec 05, 2003 at 18:30 UTC
    Interesting hack! I'd probably do this by overriding param() in a class that inherits from HTML::Template. Then just have param() autogenerate num_foo for each loop foo.

    -sam

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