=head1 NAME

HTML::Template::PerlInterface - perl interface of HTML::Template::Pro

=head1 SYNOPSIS

This help is only on perl interface of HTML::Template::Pro.
For syntax of html template files you should see 
L<HTML::Template::SYNTAX/SYNOPSIS>.

First you make a template - this is just a normal HTML file with a few
extra tags, the simplest being <TMPL_VAR>

For example, test.tmpl:

  <html>
  <head><title>Test Template</title>
  <body>
  My Home Directory is <TMPL_VAR NAME=HOME>
  <p>
  My Path is set to <TMPL_VAR NAME=PATH>
  </body>
  </html>

See L<HTML::Template::SYNTAX|HTML::Template::SYNTAX> for their syntax.

Now create a small CGI program:

  #!/usr/bin/perl -w
  use HTML::Template::Pro;

  # open the html template
  my $template = HTML::Template::Pro->new(
	filename => 'test.tmpl',
	case_sensitive=> 1);

  # fill in some parameters
  $template->param(HOME => $ENV{HOME});
  $template->param(PATH => $ENV{PATH});

  # send the obligatory Content-Type and print the template output
  print "Content-Type: text/html\n\n";

  # print output
  $template->output(print_to=>\*STDOUT);

  # this would also work.
  # print $template->output();

  # this would also work. It is faster,
  # but (WARNING!) not compatible with original HTML::Template.
  # $template->output();

If all is well in the universe this should show something like this in
your browser when visiting the CGI:

  My Home Directory is /home/some/directory
  My Path is set to /bin;/usr/bin

For the best performance it is recommended to use 
case_sensitive=>1 in new()
and print_to=>\*STDOUT in output().

Note that (HTML::Template::Pro version 0.90+) 
output(), called in void context, also prints to stdout
using built-in htmltmplpro C library calls, so the last call 
"$template->output();"
might be, in fact, the fastest way to call output().

IMPORTANT NOTE: you can safely write 

  my $template = HTML::Template->new( ... options ...)
	or even
  my $template = HTML::Template::Expr->new( ... options ...)

with HTML::Template::Pro, because in absence of original HTML::Template
and HTML::Template::Expr HTML::Template::Pro intercepts their calls.

You can also use all three modules and safely mix their calls
(benchmarking may be the only reason for it).
In case you want to mix calls to HTML::Template::Expr and 
HTML::Template::Pro, the only proper usage of their load is

use HTML::Template;
use HTML::Template::Expr;
use HTML::Template::Pro;

Of course, if you don't plan to mix them (in most cases)
it is enough to simply write

use HTML::Template::Pro;

Simply use HTML::Template::Pro, 
it supports all functions of HTML::Template::Expr.

=head1 DESCRIPTION

HTML::Template::Pro is a fast C/perl+XS implementation of HTML::Template
and HTML::Template::Expr. 
See L<HTML::Template::Pro|HTML::Template::Pro> for details.

It fully supports template language of HTML::Template 
as described in L<HTML::Template::SYNTAX|HTML::Template::SYNTAX>.

Briefly,

"This module attempts to make using HTML templates simple and natural.
It extends standard HTML with a few new HTML-esque tags - <TMPL_VAR>,
<TMPL_LOOP>, <TMPL_INCLUDE>, <TMPL_IF>, <TMPL_ELSE> and <TMPL_UNLESS>.
The file written with HTML and these new tags is called a template.
It is usually saved separate from your script - possibly even created
by someone else!  Using this module you fill in the values for the
variables, loops and branches declared in the template.  This allows
you to separate design - the HTML - from the data, which you generate
in the Perl script."

Here is described a perl interface of HTML::Template::Pro and 
HTML::Template + HTML::Template::Expr.
See B<DISTINCTIONS> for brief summary of distinctions between 
HTML::Template::Pro and HTML::Template.

=head1 METHODS

=head2 new()

Call new() to create a new Template object:

  my $template = HTML::Template->new( filename => 'file.tmpl', 
                                      option => 'value' 
                                    );

You must call new() with at least one name => value pair specifying how
to access the template text.  You can use C<< filename => 'file.tmpl' >> 
to specify a filename to be opened as the template.  Alternately you can
use:

  my $t = HTML::Template->new( scalarref => $ref_to_template_text, 
                               option => 'value' 
                             );

and

  my $t = HTML::Template->new( arrayref => $ref_to_array_of_lines , 
                               option => 'value' 
                             );


These initialize the template from in-memory resources.  In almost
every case you'll want to use the filename parameter.  If you're
worried about all the disk access from reading a template file just
use mod_perl and the cache option detailed below.

You can also read the template from an already opened filehandle,
either traditionally as a glob or as a FileHandle:

  my $t = HTML::Template->new( filehandle => *FH, option => 'value');

The four new() calling methods can also be accessed as below, if you
prefer.

  my $t = HTML::Template->new_file('file.tmpl', option => 'value');

  my $t = HTML::Template->new_scalar_ref($ref_to_template_text, 
                                        option => 'value');

  my $t = HTML::Template->new_array_ref($ref_to_array_of_lines, 
                                       option => 'value');

  my $t = HTML::Template->new_filehandle($fh, 
                                       option => 'value');

And as a final option, for those that might prefer it, you can call new as:

  my $t = HTML::Template->new(type => 'filename', 
                              source => 'file.tmpl');

Which works for all three of the source types.

If the environment variable HTML_TEMPLATE_ROOT is set and your
filename doesn't begin with /, then the path will be relative to the
value of $HTML_TEMPLATE_ROOT.  Example - if the environment variable
HTML_TEMPLATE_ROOT is set to "/home/sam" and I call
HTML::Template->new() with filename set to "sam.tmpl", the
HTML::Template will try to open "/home/sam/sam.tmpl" to access the
template file.  You can also affect the search path for files with the
"path" option to new() - see below for more information.

You can modify the Template object's behavior with new().  The options
are available:

=over 4

=item Error Detection Options

=over 4 

=item *

die_on_bad_params - if set to 0 the module will let you call
$template->param(param_name => 'value') even if 'param_name' doesn't
exist in the template body.  Defaults to 1 in HTML::Template.

HTML::Template::Pro always use die_on_bad_params => 0.
It currently can't be changed, because HTML::Template::Pro can't
know whether a parameter is bad until it finishes output.

Note that it is wrapper-only option: it is not implemented 
in the htmltmplpro C library.

=item *

force_untaint - if set to 1 the module will not allow you to set 
unescaped parameters with tainted values. If set to 2 you will have 
to untaint all parameters, including ones with the escape attribute.
This option makes sure you untaint everything so you don't accidentally
introduce e.g. cross-site-scripting (CSS) vulnerabilities. Requires 
taint mode. Defaults to 0.

In the original HTML::Template, if the "force_untaint" option is set
an error occurs if you try to set a value that is tainted in the param()
call. In HTML::Template::Pro, an error occurs when output is called.

Note that the tainted value will never be printed; but, to completely 
suppress output, one should use call to output() that returns string, 
like 
print $tmpl->output();
Then output() will die before it returns the string to print.

Note that it is wrapper-only perl-specific option: it is not 
implemented in the htmltmplpro C library.

=item *

strict - if set to 0 the module will allow things that look like they
might be TMPL_* tags to get by without dieing.  Example:

   <TMPL_HUH NAME=ZUH>

Would normally cause an error, but if you call new with strict => 0,
HTML::Template will ignore it.  Defaults to 1.

HTML::Template::Pro always implies strict => 0.

=begin comment

=item *

vanguard_compatibility_mode - if set to 1 the module will expect to
see <TMPL_VAR>s that look like %NAME% in addition to the standard
syntax.  Also sets die_on_bad_params => 0.  If you're not at Vanguard
Media trying to use an old format template don't worry about this one.
Defaults to 0.

vanguard_compatibility_mode is not supported in HTML::Template::Pro.

=end comment

=back

=item Caching Options

HTML::Template use many caching options such as 
cache, shared_cache, double_cache, blind_cache, file_cache,
file_cache_dir, file_cache_dir_mode, double_file_cache
to cache preparsed html templates.

Since HTML::Template::Pro parses and outputs templates at once,
it silently ignores those options.

=item Filesystem Options

=over 4

=item *

path - you can set this variable with a list of paths to search for
files specified with the "filename" option to new() and for files
included with the <TMPL_INCLUDE> tag.  This list is only consulted
when the filename is relative.  The HTML_TEMPLATE_ROOT environment
variable is always tried first if it exists.  Also, if
HTML_TEMPLATE_ROOT is set then an attempt will be made to prepend
HTML_TEMPLATE_ROOT onto paths in the path array.  In the case of a
<TMPL_INCLUDE> file, the path to the including file is also tried
before path is consulted.

Example:

   my $template = HTML::Template->new( filename => 'file.tmpl',
                                       path => [ '/path/to/templates',
                                                 '/alternate/path'
                                               ]
                                      );

NOTE: the paths in the path list must be expressed as UNIX paths,
separated by the forward-slash character ('/').

=item *

search_path_on_include - if set to a true value the module will search
from the top of the array of paths specified by the path option on
every <TMPL_INCLUDE> and use the first matching template found.  The
normal behavior is to look only in the current directory for a
template to include.  Defaults to 0.

=back

=item Debugging Options

=over 4

=item *

debug - if set to 1 the module will write random debugging information
to STDERR.  Defaults to 0.

=item *

HTML::Template use many cache debug options such as 
stack_debug, cache_debug, shared_cache_debug, memory_debug.
Since HTML::Template::Pro parses and outputs templates at once,
it silently ignores those options.

=back

=item Miscellaneous Options

=over 4

=item *

associate - this option allows you to inherit the parameter values
from other objects.  The only requirement for the other object is that
it have a C<param()> method that works like HTML::Template's C<param()>.  A
good candidate would be a CGI.pm query object.  Example:

  my $query = new CGI;
  my $template = HTML::Template->new(filename => 'template.tmpl',
                                     associate => $query);

Now, C<< $template->output() >> will act as though

  $template->param('FormField', $cgi->param('FormField'));

had been specified for each key/value pair that would be provided by
the C<< $cgi->param() >> method.  Parameters you set directly take
precedence over associated parameters.

You can specify multiple objects to associate by passing an anonymous
array to the associate option.  They are searched for parameters in
the order they appear:

  my $template = HTML::Template->new(filename => 'template.tmpl',
                                     associate => [$query, $other_obj]);

=begin comment

The old associateCGI() call is still supported, but should be
considered obsolete.

=end comment

NOTE: If the option case_sensitive => 0,
the parameter names are matched in a case-insensitive manner.  If
you have two parameters in a CGI object like 'NAME' and 'Name' one
will be chosen randomly by associate.  This behavior can be changed by
setting option case_sensitive to 1.

=item *

case_sensitive - setting this option to true causes HTML::Template to
treat template variable names case-sensitively.  The following example
would only set one parameter without the "case_sensitive" option:

  my $template = HTML::Template->new(filename => 'template.tmpl',
                                     case_sensitive => 1);
  $template->param(
    FieldA => 'foo',
    fIELDa => 'bar',
  );

This option defaults to off to keep compatibility with HTML::Template.
Nevertheless, setting case_sensitive => 1 is encouraged, because
it significantly improves performance.

If case_sensitive is set to 0, the perl wrapper is forced to lowercase
keys in every hash it will find in "param" tree, which is sometimes 
an expensive operation. To avoid this, set case_sensitive => 1.

If case conversion is necessary, there is an alternative lightweight
option tmpl_var_case, which is HTML::Template::Pro specific.

Note that case_sensitive is wrapper-only option: it is not implemented 
in the htmltmplpro C library.

=item *

tmpl_var_case - this option is similar to case_sensitive, but is
implemented directly in the htmltmplpro C library.
Instead of converting keys in every hash of "param" tree, it
converts the name of variable.

For example, in case of <tmpl_var name="CamelCaseName"> setting
tmpl_var_case = ASK_NAME_AS_IS | ASK_NAME_LOWERCASE | ASK_NAME_UPPERCASE
will cause HTML::Template::Pro to look into "param" tree for 3 names:
CamelCaseName, camelcasename, and CAMELCASENAME.

By default, the name is asked "as is".

=item *

loop_context_vars - when this parameter is set to true (it is false by
default) four loop context variables are made available inside a loop:
__first__, __last__, __inner__, __odd__.  They can be used with
<TMPL_IF>, <TMPL_UNLESS> and <TMPL_ELSE> to control how a loop is
output.  

In addition to the above, a __counter__ var is also made available
when loop context variables are turned on.

Example:

   <TMPL_LOOP NAME="FOO">
      <TMPL_IF NAME="__first__">
        This only outputs on the first pass.
      </TMPL_IF>

      <TMPL_IF NAME="__odd__">
        This outputs every other pass, on the odd passes.
      </TMPL_IF>

      <TMPL_UNLESS NAME="__odd__">
        This outputs every other pass, on the even passes.
      </TMPL_UNLESS>

      <TMPL_IF NAME="__inner__">
        This outputs on passes that are neither first nor last.
      </TMPL_IF>

      This is pass number <TMPL_VAR NAME="__counter__">.

      <TMPL_IF NAME="__last__">
        This only outputs on the last pass.
      </TMPL_IF>
   </TMPL_LOOP>

One use of this feature is to provide a "separator" similar in effect
to the perl function join().  Example:

   <TMPL_LOOP FRUIT>
      <TMPL_IF __last__> and </TMPL_IF>
      <TMPL_VAR KIND><TMPL_UNLESS __last__>, <TMPL_ELSE>.</TMPL_UNLESS>
   </TMPL_LOOP>

Would output (in a browser) something like:

  Apples, Oranges, Brains, Toes, and Kiwi.

Given an appropriate C<param()> call, of course.  NOTE: A loop with only
a single pass will get both __first__ and __last__ set to true, but
not __inner__.

NOTE: in the original HTML::Template with case_sensitive = 1 and loop_context_vars 
the special loop variables are available in lower-case only.
In HTML::Template::Pro they are recognized regardless of case.

=item *

no_includes - set this option to 1 to disallow the <TMPL_INCLUDE> tag
in the template file.  This can be used to make opening untrusted
templates B<slightly> less dangerous.  Defaults to 0.

=item *

max_includes - set this variable to determine the maximum depth that
includes can reach.  Set to 10 by default.  Including files to a depth
greater than this value causes an error message to be displayed.  Set
to 0 to disable this protection.

=item *

global_vars - normally variables declared outside a loop are not
available inside a loop.  This option makes <TMPL_VAR>s like global
variables in Perl - they have unlimited scope.  This option also
affects <TMPL_IF> and <TMPL_UNLESS>.

Example:

  This is a normal variable: <TMPL_VAR NORMAL>.<P>

  <TMPL_LOOP NAME=FROOT_LOOP>
     Here it is inside the loop: <TMPL_VAR NORMAL><P>
  </TMPL_LOOP>

Normally this wouldn't work as expected, since <TMPL_VAR NORMAL>'s
value outside the loop is not available inside the loop.

The global_vars option also allows you to access the values of an
enclosing loop within an inner loop.  For example, in this loop the
inner loop will have access to the value of OUTER_VAR in the correct
iteration:

   <TMPL_LOOP OUTER_LOOP>
      OUTER: <TMPL_VAR OUTER_VAR>
        <TMPL_LOOP INNER_LOOP>
           INNER: <TMPL_VAR INNER_VAR>
           INSIDE OUT: <TMPL_VAR OUTER_VAR>
        </TMPL_LOOP>
   </TMPL_LOOP>

B<NOTE>: C<global_vars> is not C<global_loops> (which does not exist).
That means that loops you declare at one scope are not available
inside other loops even when C<global_vars> is on.

=item *

path_like_variable_scope - this option switches on a Shigeki Morimoto 
extension to HTML::Template::Pro that allows access to variables that
are outside the current loop scope using path-like expressions.

Example:
{{{
<TMPL_LOOP NAME=class>
  <TMPL_LOOP NAME=person>
    <TMPL_VAR NAME="../teacher_name">  <!-- access to class.teacher_name -->
    <TMPL_VAR NAME="name">
    <TMPL_VAR NAME="/top_level_value"> <!-- access to top level value -->
    <TMPL_VAR NAME="age">
      <TMPL_LOOP NAME="../../school">  <!-- enter loop before accessing its vars -->
        <TMPL_VAR NAME="school_name">  <!-- access to [../../]school.school_name -->
      </TMPL_LOOP>
  </TMPL_LOOP>
</TMPL_LOOP>
}}}

=item *

filter - this option allows you to specify a filter for your template
files.  A filter is a subroutine that will be called after
HTML::Template reads your template file but before it starts parsing
template tags.

In the most simple usage, you simply assign a code reference to the
filter parameter.  This subroutine will receive a single argument - a
reference to a string containing the template file text.  Here is an
example that accepts templates with tags that look like "!!!ZAP_VAR
FOO!!!" and transforms them into HTML::Template tags:

   my $filter = sub {
     my $text_ref = shift;
     $$text_ref =~ s/!!!ZAP_(.*?)!!!/<TMPL_$1>/g;
   };

   # open zap.tmpl using the above filter
   my $template = HTML::Template->new(filename => 'zap.tmpl',
                                      filter => $filter);

More complicated usages are possible.  You can request that your
filter receive the template text as an array of lines rather than as
a single scalar.  To do that you need to specify your filter using a
hash-ref.  In this form you specify the filter using the C<sub> key and
the desired argument format using the C<format> key.  The available
formats are C<scalar> and C<array>.  Using the C<array> format will incur
a performance penalty but may be more convenient in some situations.

   my $template = HTML::Template->new(filename => 'zap.tmpl',
                                      filter => { sub => $filter,
                                                  format => 'array' });

You may also have multiple filters.  This allows simple filters to be
combined for more elaborate functionality.  To do this you specify an
array of filters.  The filters are applied in the order they are
specified.

   my $template = HTML::Template->new(filename => 'zap.tmpl',
                                      filter => [ 
                                           { sub => \&decompress,
                                             format => 'scalar' },
                                           { sub => \&remove_spaces,
                                             format => 'array' }
                                        ]);

The specified filters will be called for any TMPL_INCLUDEed files just
as they are for the main template file.


=back

=item * 

default_escape - Set this parameter to "HTML", "URL" or "JS" and
HTML::Template will apply the specified escaping to all variables
unless they declare a different escape in the template.

=back

=cut
















=head2 param()

C<param()> can be called in a number of ways

1) To return a list of parameters in the template : 
   ( this features is distinct in HTML::Template::Pro:
   it returns a list of parameters _SET_ after new() )

   my @parameter_names = $self->param();

2) To return the value set to a param : 

   my $value = $self->param('PARAM');

3) To set the value of a parameter :

      # For simple TMPL_VARs:
      $self->param(PARAM => 'value');

      # with a subroutine reference that gets called to get the value
      # of the scalar.  The sub will receive the template object as a
      # parameter.
      $self->param(PARAM => sub { return 'value' });   

      # And TMPL_LOOPs:
      $self->param(LOOP_PARAM => 
                   [ 
                    { PARAM => VALUE_FOR_FIRST_PASS, ... }, 
                    { PARAM => VALUE_FOR_SECOND_PASS, ... } 
                    ...
                   ]
                  );

4) To set the value of a a number of parameters :

     # For simple TMPL_VARs:
     $self->param(PARAM => 'value', 
                  PARAM2 => 'value'
                 );

      # And with some TMPL_LOOPs:
      $self->param(PARAM => 'value', 
                   PARAM2 => 'value',
                   LOOP_PARAM => 
                   [ 
                    { PARAM => VALUE_FOR_FIRST_PASS, ... }, 
                    { PARAM => VALUE_FOR_SECOND_PASS, ... } 
                    ...
                   ],
                   ANOTHER_LOOP_PARAM => 
                   [ 
                    { PARAM => VALUE_FOR_FIRST_PASS, ... }, 
                    { PARAM => VALUE_FOR_SECOND_PASS, ... } 
                    ...
                   ]
                  );

5) To set the value of a a number of parameters using a hash-ref :

      $self->param(
                   { 
                      PARAM => 'value', 
                      PARAM2 => 'value',
                      LOOP_PARAM => 
                      [ 
                        { PARAM => VALUE_FOR_FIRST_PASS, ... }, 
                        { PARAM => VALUE_FOR_SECOND_PASS, ... } 
                        ...
                      ],
                      ANOTHER_LOOP_PARAM => 
                      [ 
                        { PARAM => VALUE_FOR_FIRST_PASS, ... }, 
                        { PARAM => VALUE_FOR_SECOND_PASS, ... } 
                        ...
                      ]
                    }
                   );

=cut


=pod

=head2 clear_params()

Sets all the parameters to undef.  Useful internally, if nowhere else!


=head2 output()

output() returns the final result of the template.  In most situations
you'll want to print this, like:

   print $template->output();

When output is called each occurrence of <TMPL_VAR NAME=name> is
replaced with the value assigned to "name" via C<param()>.  If a named
parameter is unset it is simply replaced with ''.  <TMPL_LOOPS> are
evaluated once per parameter set, accumulating output on each pass.

Calling output() is guaranteed not to change the state of the
Template object, in case you were wondering.  This property is mostly
important for the internal implementation of loops.

You may optionally supply a filehandle to print to automatically as
the template is generated.  This may improve performance and lower
memory consumption.  Example:

   $template->output(print_to => *STDOUT);

The return value is undefined when using the C<print_to> option.


=head2 query()

This method is not supported in HTML::Template::Pro.

=begin comment

This method allow you to get information about the template structure.
It can be called in a number of ways.  The simplest usage of query is
simply to check whether a parameter name exists in the template, using
the C<name> option:

  if ($template->query(name => 'foo')) {
    # do something if a varaible of any type 
    # named FOO is in the template
  }

This same usage returns the type of the parameter.  The type is the
same as the tag minus the leading 'TMPL_'.  So, for example, a
TMPL_VAR parameter returns 'VAR' from C<query()>.

  if ($template->query(name => 'foo') eq 'VAR') {
    # do something if FOO exists and is a TMPL_VAR
  }

Note that the variables associated with TMPL_IFs and TMPL_UNLESSs will
be identified as 'VAR' unless they are also used in a TMPL_LOOP, in
which case they will return 'LOOP'.

C<query()> also allows you to get a list of parameters inside a loop
(and inside loops inside loops).  Example loop:

   <TMPL_LOOP NAME="EXAMPLE_LOOP">
     <TMPL_VAR NAME="BEE">
     <TMPL_VAR NAME="BOP">
     <TMPL_LOOP NAME="EXAMPLE_INNER_LOOP">
       <TMPL_VAR NAME="INNER_BEE">
       <TMPL_VAR NAME="INNER_BOP">
     </TMPL_LOOP>
   </TMPL_LOOP>

And some query calls:
  
  # returns 'LOOP'
  $type = $template->query(name => 'EXAMPLE_LOOP');
    
  # returns ('bop', 'bee', 'example_inner_loop')
  @param_names = $template->query(loop => 'EXAMPLE_LOOP');

  # both return 'VAR'
  $type = $template->query(name => ['EXAMPLE_LOOP', 'BEE']);
  $type = $template->query(name => ['EXAMPLE_LOOP', 'BOP']);

  # and this one returns 'LOOP'
  $type = $template->query(name => ['EXAMPLE_LOOP', 
                                    'EXAMPLE_INNER_LOOP']);
  
  # and finally, this returns ('inner_bee', 'inner_bop')
  @inner_param_names = $template->query(loop => ['EXAMPLE_LOOP',
                                                 'EXAMPLE_INNER_LOOP']);

  # for non existent parameter names you get undef
  # this returns undef.
  $type = $template->query(name => 'DWEAZLE_ZAPPA');

  # calling loop on a non-loop parameter name will cause an error.
  # this dies:
  $type = $template->query(loop => 'DWEAZLE_ZAPPA');

As you can see above the C<loop> option returns a list of parameter
names and both C<name> and C<loop> take array refs in order to refer
to parameters inside loops.  It is an error to use C<loop> with a
parameter that is not a loop.

Note that all the names are returned in lowercase and the types are
uppercase.

Just like C<param()>, C<query()> with no arguments returns all the
parameter names in the template at the top level.

=end comment

=cut

=head1 DISTINCTIONS AND INCOMPATIBILITIES

The main reason for small incompatibilities between HTML::Template and
HTML::Template::Pro is the fact that HTML::Template builds parsed tree of 
template before anything else. So it has an additional information
which HTML::Template::Pro obtains during output.

In cases when HTML::Template dies, such as no_includes,
bad syntax of template, max_includes and so on, 
HTML::Template::Pro issues warning to STDERR and continue.


=head2 new()

the following options are not supported in HTML::Template::Pro:

 vanguard_compatibility_mode.

The options die_on_bad_params and strict are ignored.
HTML::Template::Pro behaves itself as HTML::Template called with 
 die_on_bad_params => 0, strict => 0. 

It currently can't be changed, because HTML::Template::Pro can't
know whether a parameter is bad before it start output.
This may change in future releases.

To keep backward compatibility with HTML::Template, you should 
explicitly call its new() with die_on_bad_params => 0, strict => 0.

=head2 query()

This method is not supported in HTML::Template::Pro.

=head2 param()

param() without arguments should return a list of parameters in the template.
In HTML::Template::Pro it returns a list of parameters set after new(). 

=head1 BUGS

With I<case_sensitive> and I<loop_context_vars> the special loop
variables should be available in lower-case only.

I<associate> is case_sensitive inside loops.

=begin comment

I am aware of no bugs - if you find one, join the mailing list and
tell us about it.  You can join the HTML::Template mailing-list by
visiting:

  http://lists.sourceforge.net/lists/listinfo/html-template-users

Of course, you can still email me directly (sam@tregar.com) with bugs,
but I reserve the right to forward bug reports to the mailing list.

=end comment

When submitting bug reports, be sure to include full details,
including the VERSION of the module, a test script and a test template
demonstrating the problem!

=begin comment

If you're feeling really adventurous, HTML::Template has a publically
available Subversion server.  See below for more information in the PUBLIC
SUBVERSION SERVER section.

=end comment






=head1 EXPR: DEFINING NEW FUNCTIONS

To define a new function, pass a C<functions> option to new:

  $t = HTML::Template::Pro->new(filename => 'foo.tmpl',
                                 functions => 
                                   { func_name => \&func_handler });
or

  $t = HTML::Template::Expr->new(filename => 'foo.tmpl',
                                 functions => 
                                   { func_name => \&func_handler });

Or, you can use C<register_function> class method to register
the function globally:

  HTML::Template::Pro->register_function(func_name => \&func_handler);
or 
  HTML::Template::Expr->register_function(func_name => \&func_handler);

You provide a subroutine reference that will be called during output.
It will receive as arguments the parameters specified in the template.
For example, here's a function that checks if a directory exists:

  sub directory_exists {
    my $dir_name = shift;
    return 1 if -d $dir_name;
    return 0;
  }

If you call HTML::Template::Expr->new() with a C<functions> arg:

  $t = HTML::Template::Expr->new(filename => 'foo.tmpl',
                                 functions => {
                                    directory_exists => \&directory_exists
                                 });

Then you can use it in your template:

  <tmpl_if expr="directory_exists('/home/sam')">

This can be abused in ways that make my teeth hurt.

=head2 register_function() extended usage (HTML::Template::Pro specific)

C<register_function()> can be called in a number of ways

1) To fetch the names of registered functions in the template:

=over 4

=item *
   if C<register_function()> was called in a newly created object it returns a

   list of function's that set _after_ or _in_ new():

   my @registered_functions_names = $self->register_function();

=item *
   in global context C<register_function()> will return a list of _ALL_
   avalible function's

   my @all_avalible_functions_names =
HTML::Template::Pro->register_function();

2) To fetching the function by name:

   my $function = $self->register_function('FUNCTION_NAME');

3) To set a new function:

    # Set function, that can be called in templates, wich are processed
    # by the current object:
    $self->register_function(foozicate => sub { ... });

    # Set global function:
    HTML::Template::Pro->register_function(barify    => sub { ... });

=back

for details of "how to defined a function" see in
L<EXPR: DEFINING NEW FUNCTIONS>.

=head1 EXPR MOD_PERL TIP

C<register_function> class method can be called in mod_perl's
startup.pl to define widely used common functions to
HTML::Template::Expr. Add something like this to your startup.pl:

  use HTML::Template::Pro;

  HTML::Template::Pro->register_function(foozicate => sub { ... });
  HTML::Template::Pro->register_function(barify    => sub { ... });
  HTML::Template::Pro->register_function(baznate   => sub { ... });

=head1 EXPR CAVEATS

HTML::Template::Pro does not forces the HTML::Template global_vars 
option to be set, whereas currently HTML::Template::Expr does.
Anyway, this also will hopefully go away in a future version of 
HTML::Template::Expr, so if you need global_vars in your templates 
then you should set it explicitly.







=head1 CREDITS

to Sam Tregar, sam@tregar.com

Original credits of HTML::Template:

This module was the brain child of my boss, Jesse Erlbaum
( jesse@vm.com ) at Vanguard Media ( http://vm.com ) .  The most original
idea in this module - the <TMPL_LOOP> - was entirely his.

Fixes, Bug Reports, Optimizations and Ideas have been generously
provided by:

   Richard Chen
   Mike Blazer
   Adriano Nagelschmidt Rodrigues
   Andrej Mikus
   Ilya Obshadko
   Kevin Puetz
   Steve Reppucci
   Richard Dice
   Tom Hukins
   Eric Zylberstejn
   David Glasser
   Peter Marelas
   James William Carlson
   Frank D. Cringle
   Winfried Koenig
   Matthew Wickline
   Doug Steinwand
   Drew Taylor
   Tobias Brox
   Michael Lloyd
   Simran Gambhir
   Chris Houser <chouser@bluweb.com>
   Larry Moore
   Todd Larason
   Jody Biggs
   T.J. Mather
   Martin Schroth
   Dave Wolfe
   uchum
   Kawai Takanori
   Peter Guelich
   Chris Nokleberg
   Ralph Corderoy
   William Ward
   Ade Olonoh
   Mark Stosberg
   Lance Thomas
   Roland Giersig
   Jere Julian
   Peter Leonard
   Kenny Smith
   Sean P. Scanlon
   Martin Pfeffer
   David Ferrance
   Gyepi Sam  
   Darren Chamberlain
   Paul Baker
   Gabor Szabo
   Craig Manley
   Richard Fein
   The Phalanx Project
   Sven Neuhaus

Thanks!

Original credits of HTML::Template::Expr:

The following people have generously submitted bug reports, patches
and ideas:

   Peter Leonard
   Tatsuhiko Miyagawa

Thanks!


=head1 WEBSITE

You can find information about HTML::Template::Pro at:

   http://html-tmpl-pro.sourceforge.net

You can find information about HTML::Template and other related modules at:

   http://html-template.sourceforge.net

=begin comment

=head1 PUBLIC SUBVERSION SERVER

HTML::Template now has a publicly accessible Subversion server
provided by SourceForge (www.sourceforge.net).  You can access it by
going to http://sourceforge.net/svn/?group_id=1075.  Give it a try!

=end comment

=head1 AUTHOR

Sam Tregar, sam@tregar.com (Main text)

I. Vlasenko, E<lt>viy@altlinux.orgE<gt> (Pecularities of HTML::Template::Pro)

=head1 LICENSE

  HTML::Template : A module for using HTML Templates with Perl
  Copyright (C) 2000-2002 Sam Tregar (sam@tregar.com)

  This module is free software; you can redistribute it and/or modify it
  under the terms of either:

  a) the GNU General Public License as published by the Free Software
  Foundation; either version 1, or (at your option) any later version,
  
  or

  b) the "Artistic License" which comes with this module.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See either
  the GNU General Public License or the Artistic License for more details.

  You should have received a copy of the Artistic License with this
  module, in the file ARTISTIC.  If not, I'll be glad to provide one.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  USA

=cut
