Hello world (from command-line)

    % mason
    Hello! The local time is <% scalar(localtime) %>.
    ^D

(where '^D' means ctrl-D or EOF). You should see something like

    Hello! The local time is Wed Mar  2 17:11:54 2011.

The "mason" command reads in a Mason component (template), runs it, and prints the result to standard output. Notice that the tag

    <% scalar(localtime) %>

was replaced with the value of its expression. This is called a substitution tag and is a central piece of Mason syntax.

Email generator (from script)

In a test directory, create a directory "comps" and create a file "email.mc" with the following:

    <%class>
    has 'amount';
    has 'name';
    </%class>

    Dear <% $.name %>,

        We are pleased to inform you that you have won $<% sprintf("%.2f", $.amount) %>!

    Sincerely,
    The Lottery Commission

    <%init>
    die "amount must be a positive value!" unless $.amount > 0;
    </%init>

In addition to the substitution tag we've seen before, we declare two attributes, "amount" and "name", to be passed into the component; and we declare a piece of initialization code to validate the amount.

In the same test directory, create a script "test.pl" with the following:

     1  #!/usr/local/bin/perl
     2  use Mason;
     3  my $interp = Mason->new(comp_root => 'comps', data_dir => 'data');
     4  print $interp->run('/email', name => 'Joe', amount => '1500')->output;

Line 3 creates a Mason interpreter, the main Mason object. It specifies two parameters: a component root, indicating the directory hierarchy where your components will live; and a data directory, which Mason will use for internal purposes such as class generation and caching.

Line 4 runs the template - notice that the ".mc" extension is added automatically - passing values for the "name" and "amount" attributes.

Run "test.pl", and you should see

    Dear Joe,

        We are pleased to inform you that you have won $1500.00!

    Sincerely,
    The Lottery Commission