NAME

Petal::CodePerl - Make Petal go faster by compiling the expressions

SYNOPSIS

  use Petal::CodePerl;

  # contnue as you would normally use Petal

or

  use Petal;
        $Petal::CodeGenerator = 'Petal::CodePerl::CodeGenerator';
        
  # contnue as you would normally use Petal

DESCRIPTION

This module provides a CodeGenerator for Petal that inherits almost everything from Petal::CodeGenerator but modifies how expressions are dealt with. Petal normally includes code like this

  $hash->get( "not:user" )

in the compiled template. This means the path has to be parsed and interpreted at runtime. Using Petal::CodePerl, Petal will now produce this

  ! ($hash->{"user"})

which will be much faster.

It uses Parse::RecDescent to parse the PETALES expressions which makes it a bit slow to load the module but this won't matter much unless you have turned off caching. It won't matter at all for something like Apache's mod_perl.

USAGE

You have two choices, you can replace use Petal with use Petal::CodePerl in all your scripts or you can do $Petal::CodeGenerator = 'Petal::CodePerl::CodeGenerator'. Either of these will cause Petal to use the expression compiling version of the CodeGenerator.

EXTRA BONUSES

Using Parse::RecDescent makes it easier to expand the PETALES grammar. I have made the following enhancements.

• alternators work as in TAL, so you can do

    petal:content="a/name|b/name|string:no name"

• you can explicitly ask for hash, array or method in a path

  • user{name} is $hash->{"user"}->{"name"}

  • user[1] is $hash->{"user"}->[1]

  • user/method() is $hash->{"user"}->method()

    using these will make your template even faster although you need to be certain of your data types.

• method arguments can be any expression for example

    user/purchase cookie{basket}
    

  will give

    $hash->{"user"}->purchase($hash->{"cookie"}->{"basket"})

• you can do more complex defines, like the followiing

    petal:define="a{b}[1] string:hello"

  which will give

    $hash->{"a"}->[1] = "hello"

• some other stuff that I can't remember just now.

STATUS

Petal::CodePerl is in development. There are no known bugs and Petal passes it's full test suite using this code generator. However there are probably some differences between it's grammar and Petal's current grammar. Please let me know if you find anything that works differently with Petal::CodePerl.

PROBLEMS

One slight problem is the handling of non-standard modifers. It is not possible to use modifiers AND compiled expressions together, so expressions that use modifiers will not be compiled at all, they will be evaluated at runtime by Petal using $hash->get( $expression ). So basically expressions that start with anything other than "string:", "not:", "path:", "exists:", "perl:" will not gain any speedup.

Your templates may now generate "undefined value" warnings if you try to use an undefined value. Previously, Petal prevented many of these from occurring. As always, the best thing to do is not to avoid using undefined values in your templates.

AUTHOR

Written by Fergal Daly <fergal@esatclear.ie>.

COPYRIGHT

Copyright 2003 by Fergal Daly <fergal@esatclear.ie>.

This program is free software and comes with no warranty. It is distributed under the LGPL license

See the file LGPL included in this distribution or http://www.fsf.org/licenses/licenses.html.