NAME

Text::MicroMason - Simple and Extensible Templating

SYNOPSIS

Mason syntax provides several ways to mix Perl into a text template:

    <%args>
      $name
    </%args>
    % if ( $name eq 'Dave' ) {
      I'm sorry <% $name %>, I'm afraid I can't do that right now.
    % } else {
      <%perl>
        my $hour = (localtime)[2];
        my $daypart = ( $hour > 11 ) ? 'afternoon' : 'morning'; 
      </%perl>
      Good <% $daypart %>, <% $name %>!
    % }

Create a MicroMason object to interpret the templates:

    use Text::MicroMason;
    $mason = Text::MicroMason->new();

Use the compile method to convert templates into a subroutines:

    $coderef = $mason->compile( text=>$template );
    print $coderef->('name'=>'Alice');

Or use the execute method to parse and evaluate in one call:

    print $mason->execute( text=>$template, 'name'=>'Bob' );

Templates stored in files can be run directly or included in others:

    print $mason->execute( file=>"./greeting.msn", 'name'=>'Charles');

For additional features, select mixin classes to add to your MicroMason object:

    $mason = Text::MicroMason->new( qw( -CatchErrors -Safe -Filters ) );

You can import various functions if you prefer to avoid method calls:

    use Text::MicroMason::Functions qw( compile execute );

    print execute($template, 'name'=>'Dave');

    $coderef = compile($template);
    print $coderef->('name'=>'Bob');

DESCRIPTION

Text::MicroMason interpolates blocks of Perl code embedded into text strings.

Each MicroMason object acts as a "template compiler," which converts templates from text-with-embedded-code formats into ready-to-execute Perl subroutines.

MicroMason Initialization

Use the new() method to create a Text::MicroMason object with the appropriate mixins and attributes.

  $mason = Text::MicroMason->new( %attribs );

You may pass attributes as key-value pairs to the new() method to save various options for later use by the compile() method.

Template Compilation

To compile a text template, pass it to the compile() method to produce a new Perl subroutine to be returned as a code reference:

  $code_ref = $mason->compile( $type => $source, %attribs );

Any attributes provided to compile() will temporarily override the persistent options defined by new(), for that template only.

You can provide the template as a text string, a file name, or an open file handle:

  $code_ref = $mason->compile( text => $template );
  $code_ref = $mason->compile( text => \$template );
  $code_ref = $mason->compile( file => $filename );
  $code_ref = $mason->compile( handle => $fh );
  $code_ref = $mason->compile( handle => \*FILE );

Template files are just plain text files that contains the string to be parsed. The files may have any name and extension you wish. The filename specified can either be absolute or relative to the program's current directory.

Template Execution

To execute the template and obtain the output, call a compiled function:

  $result = $code_ref->( @arguments );

(Note that the $code_ref->() syntax is unavailable in older versions of Perl; use the equivalent &$code_ref() syntax instead.)

As a shortcut, the execute method compiles and runs the template one time:

  $result = $mason->execute( $type => $source, @arguments );
  $result = $mason->execute( $type => $source, \%attribs, @arguments );

Argument Passing

You can pass arguments to a template subroutine using positional or named arguments.

For positional arguments, pass the argument list and read from @_ as usual:

  $mason->compile( text=>'Hello <% shift(@_) %>.' )->( 'Dave' );

For named arguments, pass in a hash of key-value pairs to be made accessible in an %ARGS hash within the template subroutine:

  $mason->compile( text=>'Hello <% $ARGS{name} %>.' )->( name=>'Dave' );

Additionally, you can use named arguments with the %args block syntax:

  $mason->compile( text=>'<%args>$name</%args>Hello <% $name %>.' )->( name=>'Dave' );

Mixin Selection

Arguments passed to new() that begin with a dash will be added as mixin classes.

  $mason = Text::MicroMason->new( -Mixin1, %attribs, -Mixin2 );

Every MicroMason object inherits from an abstract Base class and some set of mixin classes. By combining mixins you can create subclasses with the desired combination of features. See Text::MicroMason::Base for documentation of the base class, including private methods and extension mechanisms.

If you call the new method on Text::MicroMason, it automatically includes the HTMLMason mixin, which provides the standard template syntax. If you want to create an object without the default HTMLMason functionality, call Text::MicroMason::Base->new() instead.

Some mixins define the syntax for a particular template format. You will generally need to select one, and only one, of the mixins listed in "TEMPLATE SYNTAXES".

Other mixins provide optional functionality. Those mixins may define additional public methods, and may support or require values for various additional attributes. For a list of such mixin classes, see "MIXIN FEATURES".

TEMPLATE SYNTAXES

Templates contain a mix of literal text to be output with some type of markup syntax which specifies more complex behaviors.

The Text::MicroMason::HTMLMason mixin is selected by default. To enable an alternative, pass its name to Text::MicroMason::Base->new( - MixinName ).

HTMLMason

The HTMLMason mixin provides lexer and assembler methods that handle most elements of HTML::Mason's template syntax.

  my $mason = Text::MicroMason::Base->new( -HTMLMason );
  my $output = $mason->execute( text => $template, name => 'Bob' );

    <%args>
      $name => 'Guest' 
    </%args>

    % if ( $name eq 'Dave' ) {
      I'm sorry <% $name %>, I'm afraid I can't do that right now.
    % } else {
      <%perl>
        my $hour = (localtime)[2];
        my $daypart = ( $hour > 11 ) ? 'afternoon' : 'morning'; 
      </%perl>
      Good <% $daypart %>, <% $name %>!
    % }

    <& "includes/standard_footer.msn" &>

    <%doc>
      Here's a private developr comment describing this template. 
    </%doc>

For a definition of the template syntax, see Text::MicroMason::HTMLMason.

DoubleQuote

The DoubleQuote mixin uses Perl's double-quoting interpolation as a minimalist syntax for templating.

  my $mason = Text::MicroMason::Base->new( -DoubleQuote );
  my $output = $mason->execute( text => $template, name => 'Bob' );

    ${ $::hour = (localtime)[2];
      $::daypart = ( $::hour > 11 ) ? 'afternoon' : 'morning'; 
    \'' }
    Good $::daypart, $ARGS{name}!

For more information see Text::MicroMason::DoubleQuote.

Embperl

The Embperl mixin support a template syntax similar to that used by the HTML::Embperl module.

  my $mason = Text::MicroMason::Base->new( -Embperl );
  my $output = $mason->execute( text => $template, name => 'Bob' );

    [- my $name = $ARGS{name}; -]
    [$ if $name eq 'Dave' $]
      I'm sorry [+ $name +], I'm afraid I can't do that right now.
    [$ else $]
      [- 
        my $hour = (localtime)[2];
        my $daypart = ( $hour > 11 ) ? 'afternoon' : 'morning'; 
      -]
      Good [+ $daypart +], [+ $name +]!
    [$ endif $]

For more information see Text::MicroMason::Embperl.

HTMLTemplate

The HTMLTemplate mixin supports a syntax similar to that used by the HTML::Template module.

  my $mason = Text::MicroMason::Base->new( -HTMLTemplate );
  my $output = $mason->execute( text => $template, name => 'Bob' );

    <TMPL_IF NAME="user_is_dave">
      I'm sorry <TMPLVAR NAME="name">, I'm afraid I can't do that right now.
    <TMPL_ELSE>
      <TMPL_IF NAME="daytime_is_morning">
        Good morning, <TMPLVAR NAME="name">!
      <TMPL_ELSE>
        Good afternoon, <TMPLVAR NAME="name">!
      </TMPL_IF>
    </TMPL_IF>

For more information see Text::MicroMason::HTMLTemplate.

ServerPages

The ServerPages mixin supports a syntax similar to that used by the Apache::ASP module.

  my $mason = Text::MicroMason::Base->new( -ServerPages );
  my $output = $mason->execute( text => $template, name => 'Bob' );

    <% my $name = $ARGS{name};
      if ( $name eq 'Dave' ) {  %>
      I'm sorry <%= $name %>, I'm afraid I can't do that right now.
    <% } else { 
        my $hour = (localtime)[2];
        my $daypart = ( $hour > 11 ) ? 'afternoon' : 'morning'; 
      %>
      Good <%= $daypart %>, <%= $name %>!
    <% } %>

For more information see Text::MicroMason::ServerPages.

Sprintf

The Sprintf mixin uses Perl's sprintf formatting syntax for templating.

  my $mason = Text::MicroMason::Base->new( -Sprintf );
  my $output = $mason->execute( text => $template, 'morning', 'Bob' );

    Good %s, %s!

For more information see Text::MicroMason::Sprintf.

TextTemplate

The TextTemplate mixin supports a syntax similar to that used by the Text::Template module.

  my $mason = Text::MicroMason::Base->new( -TextTemplate );
  my $output = $mason->execute( text => $template, name => 'Bob' );

    { $hour = (localtime)[2];
      $daypart = ( $hour > 11 ) ? 'afternoon' : 'morning'; 
    '' }
    Good { $daypart }, { $name }!

For more information see Text::MicroMason::TextTemplate.

MIXIN FEATURES

The following mixin classes can be layered on to your MicroMason object to provide additional functionality.

To add a mixin's functionality, pass it's name with a dash to the new() method:

  $mason = Text::MicroMason->new( -CatchErrors, -PostProcess );

AllowGlobals

Enables access to a set of package variables to be shared with templates.

For details see Text::MicroMason::AllowGlobals.

CatchErrors

Both compilation and run-time errors in your template are handled as fatal exceptions. To prevent a template error from ending your program, enclose it in an eval block:

  my $result = eval { $mason->execute( text => $template ) };
  if ( $@ ) {
    print "Unable to execute template: $@";
  } else {
    print $result;
  }

To transparently add this functionality to your MicroMason object, see Text::MicroMason::CatchErrors.

CompileCache

Calling execute repeatedly will be slower than compiling once and calling the template function repeatedly, unless you enable compilation caching.

For details see Text::MicroMason::CompileCache.

Debug

When trying to debug a template problem, it can be helpful to watch the internal processes of template compilation. This mixin adds controllable warning messages that show the intermediate parse information.

For details see Text::MicroMason::Debug.

LineNumbers

Provide better line numbers when compilation fails, at the cost of potentially slower compilation and execution.

For details see Text::MicroMason::LineNumbers.

ExecuteCache

Each time you execute the template all of the logic will be re- evaluated, unless you enable execution caching, which stores the output of each template for each given set of arguments.

For details see Text::MicroMason::ExecuteCache.

Filters

HTML::Mason provides an expression filtering mechanism which is typically used for applying HTML and URL escaping functions to output.

  Text::MicroMason->new(-Filters)->compile( text => $template );

  <p> Hello <% $name |h %>!

The Filters mixin provides this capability for Text::MicroMason templates. To select it, add its name to your Mason initialization call:

  my $mason = Text::MicroMason->new( -Filters );

Output expressions may then be followed by "|h" or "|u" escapes; for example this line would convert any ampersands in the output to the equivalent HTML entity:

  Welcome to <% $company_name |h %>

For more information see Text::MicroMason::Filters.

PassVariables

Allows you to pass arguments to templates as variables instead of the basic argument list.

For details see Text::MicroMason::PostProcess.

PostProcess

Allows you to specify one or more functions through which all template output should be passed before it is returned.

For details see Text::MicroMason::PostProcess.

Safe

By default, the code embedded in a template has accss to all of the capabilities of your Perl process, and could potentially perform dangerous activities such as accessing or modifying files and starting other programs.

If you need to execute untrusted templates, use the Safe module, which can restrict the operations and data structures that template code can access.

To add this functionality to your MicroMason object, see Text::MicroMason::Safe.

TemplateDir

The filenames passed to the compile() or execute() methods can be looked up relative to a base directory path or the current template file.

To add this functionality to your MicroMason object, see Text::MicroMason::TemplateDir.

TemplatePath

The filenames passed to the compile() or execute() methods are looked up relative to a list of multiple base directory paths, in order. It tries as hard as possible to maintain compatibility with caching and <& &> template includes.

To add this functionality to your MicroMason object, see Text::MicroMason::TemplatePath.

OTHER INTERFACES

Function Exporter

Importable functions are provided for users who prefer a procedural interface.

The supported functions are listed in Text::MicroMason::Functions. (For backwards compatibility, those functions can also be imported from the main Text::MicroMason package.)

Template Frameworks

Adaptor modules are available to use MicroMason from within other frameworks. For more information, see Any::Template::Backend::Text::MicroMason and Catalyst::View::MicroMason.

Inline

MicroMason templates can be embbeded within your source code using Inline. For more information, see Inline::Mason.

EXCEPTIONS

Text::MicroMason croaks on error, with an appropriate error string. Some commonly occurring error messages are described below (where %s indicates variable message text). See also the pod for each mixin class, for additional exception strings that may be thrown.

MicroMason parsing halted at %s
Indicates that the parser was unable to finish tokenising the source text. Generally this means that there is a bug somewhere in the regular expressions used by lex().

(If you encounter this error, please feel free to file a bug report or send an example of the error to the author using the addresses below, and I'll attempt to correct it in a future release.)
MicroMason compilation failed: %s
The template was parsed successfully, but the Perl subroutine declaration it was converted to failed to compile. This is generally a result of a syntax error in one of the Perl expressions used within the template.
Error in template subroutine: %s
Additional diagnostic for compilation errors, showing the text of the subroutine which failed to compile.
Error in template file %s, interpreted as: %s
Additional diagnostic for compilation errors in external files, showing the filename and the text of the subroutine which failed to compile.
MicroMason execution failed: %s
After parsing and compiling the template successfully, the subroutine was run and caused a fatal exception, generally because that some Perl code used within the template caused die() to be called (or an equivalent function like croak or confess).
MicroMason: filename is missing or empty
One of the compile or execute methods was called with an empty or undefined filename, or one of the compile_file or execute_file methods was called with no arguments.
MicroMason can't read from %s: %s
One of the compile_file or execute_file functions was called but we were unable to read the requested file, because the file path is incorrect or we have insufficient privileges to read that file.
[Reference / Object]
If the code inside the template throws a reference or object while calling die(), MicroMason will re-throw the reference to the calling code.