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 evalute 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 priveleges to read that file.
SEE ALSO¶
For distribution, installation, support, copyright and license information, see
Text::MicroMason::Docs::ReadMe.