NAME

Template::Perlish - Yet Another Templating system for Perl

VERSION

This document describes Template::Perlish version 1.0. Most likely, this version number here is outdate, and you should peek the source.

SYNOPSIS

use Template::Perlish;

my $tp = Template::Perlish->new();

# A complex template, including some logic as Perl code
my $tmpl = <<END_OF_TEMPLATE
Dear [% name %],

   we are pleased to present you the following items:
[%
   my $items = $variables{items}; # Available %variables
   for my $item (@$items) {%]
   * [% print $item;
   }
%]

Please consult our complete catalog at [% uris.2.catalog %].

Yours,

   [% director.name %] [% director.surname %].
END_OF_TEMPLATE

my $processed = $tt->process($template, {
   name => 'Ciccio Riccio',
   items => [ qw( ciao a tutti quanti ) ],
   uris => [
      'http://whatever/',
      undef,
      {
         catalog => 'http://whateeeeever/',
      }
   ],
   director => { surname => 'Poletti' },
});

# The above prints:
#
#   Dear Ciccio Riccio,
#   
#      we are pleased to present you the following items:
#   
#      * ciao
#      * a
#      * tutti
#      * quanti
#   
#   Please consult our complete catalog at http://whateeeeever/.
#   
#   Yours,
#   
#       Poletti.

DESCRIPTION

You bet, this is another templating system for Perl. Yes, because it's the dream of every Perl programmer, me included. I needed something that's easily portable, with no dependencies apart a recent Perl version (but with some tweaking this should be solved), much in the spirit of the ::Tiny modules. And yes, my dream is to fill that ::Tiny gap some time in the future, but with another module.

Wherever possible I try to mimic Template::Toolkit, but I stop quite early. If you only have to fill a template with a bunch of variables, chances are that TT2 templates are good for Template::Perlish as well. If you need even the slightest bit of logic, you'll have to part from TT2 - and get full Perl power.

A template is simply a text (even if not necessarily) with some particular markup to embed commands. In particular, all the stuff included between [% and %] is considered as some sort of command, and treated specially. All the rest is treated as simple text. Of course, you can modify the start and stop delimiter for a command.

Commands can be of two different types:

variable embedding

that are expanded with the particular value for a given variable, where variables are passed as a hash reference. A variable can be defined as a sequence of alphanumeric (actually \w) tokens, separated by dots. The variables hash is visited considering each token as a subkey, in order to let you visit complex data structures. You can also put arrays in, but remember to use numbers ;)

code

good old Perl code, in order to provide you with control structures, modules, etc etc. This the most lazy approach I could think about, and it's also why this module is called Perlish.

Take a look at the example in the SYNOPSIS, it actually contains all that this module provides.

To start, you'll need a Template::Perlish object and, of course, a template. Templates are provided as text strings; if you have them into files, you are in charge of loading them first.

# get a Template::Perlish object
my $tp = Template::Perlish->new();

# get the template (yes, it's your duty)
my $tmpl = do { open my $fh, '<', 'filename'; local $/; <$fh> };

The basic operation mode is via the process() method, which works much like in TT2. Anyway, this method will always give you back the generated stuff, and won't print anything. This can probably be less memory efficient when big templates are involved, but in this case you should probably head somewhere else.

# print out the template filled with some variables
print $tp->process($tmpl, { key => 'value' });

Each template is transformed into Pure Perl code, then the code is evaluated in order to get the output. Thus, if you want to operate on the same template many times, a typical usage is:

# compile the template with something like:
my $compiled = $tp->compile($template);

# use the compiled template multiple times with different data
for my $dataset (@available_data) {
   print {*STDOUT} "DATASET\n", $tp->evaluate($dataset), "\n\n";
}

INTERFACE

Constructor and Accessors

new(%opts)

new(\%opts)

constructor, does exactly what you think. You can provide any parameter, but only the following will make sense:

start

delimiter for the start of a command (as opposed to plain text/data);

stop

delimiter for the end of a command;

variables

variables that will be passed to all invocations of process() and/or evaluate().

Parameters can be given directly or via a hash reference.

By default, the delimiters are the same as TT2, i.e. [% and %], and the variables hash is empty.

get_start(), set_start($value)

get_stop(), set_stop($value)

accessors for the delimiters (see new()).

get_variables()

get the configured variables. These variables will be available to all invocations of either process() or evaluate().

When called in scalar context returns a reference to the hash containing the variables. You can set variables directly on the hash. In list context the whole hash will be returned (as a shallow copy).

set_variables(%new_values)

set_variables(\%new_values)

set variables common to all subsequent invocations. You can pass either the new contents for the hash, or a reference to the hash to be used.

set_variable($name, $value)

set a single variable's value, among the variables that are passed to all invocations.

Template Handling

compile($template)

compile a template generating the relevant Perl code. Using this method is useful when the same template has to be used multiple times, so the compilation can be done one time only.

Please note that the generated Perl code will be parsed each time you use it, of course.

Returns a text containing Perl code.

evaluate($compiled)

evaluate($compiled, $variables)

evaluate a template (in its compiled for, see compile()) with the available variables. In the former form, only the already configured variables are used; in the latter, the given $variables (which is a hash reference) are added, overriding any matching key.

Returns the processed text as a string.

process($template)

process($template, $variables)

this method included compile() and evaluate() into a single step.

Templates

There's really very little to say.

Available variables can be accessed in two ways: using the dotted notation, as in

[% some.value.3.lastkey %]

or explicitly using the %variables hash:

[% print $variables{some}{value}[3]{lastkey} %]

The former is cleaner, but the latter is more powerful of course.

If you know Perl, you should not have problems using the control structures. Just intersperse the code with the templates as you would normally do in any other templating system:

[%
   if ($variables{this}) {
%]
     blah blah [% this %], foo bar!
[%
   }
   else {
%]
     yak yak that!
[%
   }
%]

Take care to always terminate your commands with a ; each time you would do it in actual code.

There's no escaping mechanism, so if you want to include literal [% or %] you either have to change delimiters, or you have to resort to tricks. In particular, a stray closing inside a textual part won't be a problem, e.g.:

[% print "variable"; %] %] [% print "another"; %]

prints:

variable %] another

The tricky part is including the closing in the Perl code, but there can be many tricks:

[% print '>>>%'.']<<<' %]

prints

>>>%]<<<

To include a starter in the text just print it inside a Perl block:

here it comes [% print '[%'; %] the delimiter

prints:

here it comes [% the delimiter

Another trick is to separate the two chars with an empty block:

here it comes [[%%]%

Including the starter in the Perl code is not a problem, of course.

So the bottom line is: who needs escaping?

DIAGNOSTICS

Unfortunately, the diagnostic is still quite poor.

open(): %s

the only open() is done to print stuff to a string. If you get this error, you're probably using a version of Perl that's too old.

unclosed %s at position %d

a Perl block was opened but not closed.

CONFIGURATION AND ENVIRONMENT

Template::Perlish requires no configuration files or environment variables.

DEPENDENCIES

None, apart a fairly recent version of Perl.

INCOMPATIBILITIES

None reported.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests through http://rt.cpan.org/

Due to the fact that Perl code is embedded directly into the template, you have to take into consideration all the possible security implications.

AUTHOR

Flavio Poletti <flavio [at] polettix [dot] it>

LICENCE AND COPYRIGHT

Copyright (c) 2008, Flavio Poletti <flavio [at] polettix [dot] it>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic and perlgpl.

Questo modulo è software libero: potete ridistribuirlo e/o modificarlo negli stessi termini di Perl stesso. Vedete anche perlartistic e perlgpl.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

NEGAZIONE DELLA GARANZIA

Poiché questo software viene dato con una licenza gratuita, non c'è alcuna garanzia associata ad esso, ai fini e per quanto permesso dalle leggi applicabili. A meno di quanto possa essere specificato altrove, il proprietario e detentore del copyright fornisce questo software "così com'è" senza garanzia di alcun tipo, sia essa espressa o implicita, includendo fra l'altro (senza però limitarsi a questo) eventuali garanzie implicite di commerciabilità e adeguatezza per uno scopo particolare. L'intero rischio riguardo alla qualità ed alle prestazioni di questo software rimane a voi. Se il software dovesse dimostrarsi difettoso, vi assumete tutte le responsabilità ed i costi per tutti i necessari servizi, riparazioni o correzioni.

In nessun caso, a meno che ciò non sia richiesto dalle leggi vigenti o sia regolato da un accordo scritto, alcuno dei detentori del diritto di copyright, o qualunque altra parte che possa modificare, o redistribuire questo software così come consentito dalla licenza di cui sopra, potrà essere considerato responsabile nei vostri confronti per danni, ivi inclusi danni generali, speciali, incidentali o conseguenziali, derivanti dall'utilizzo o dall'incapacità di utilizzo di questo software. Ciò include, a puro titolo di esempio e senza limitarsi ad essi, la perdita di dati, l'alterazione involontaria o indesiderata di dati, le perdite sostenute da voi o da terze parti o un fallimento del software ad operare con un qualsivoglia altro software. Tale negazione di garanzia rimane in essere anche se i dententori del copyright, o qualsiasi altra parte, è stata avvisata della possibilità di tali danneggiamenti.

Se decidete di utilizzare questo software, lo fate a vostro rischio e pericolo. Se pensate che i termini di questa negazione di garanzia non si confacciano alle vostre esigenze, o al vostro modo di considerare un software, o ancora al modo in cui avete sempre trattato software di terze parti, non usatelo. Se lo usate, accettate espressamente questa negazione di garanzia e la piena responsabilità per qualsiasi tipo di danno, di qualsiasi natura, possa derivarne.

cpanm Template::Perlish

perl -MCPAN -e shell
install Template::Perlish