Ubuntu Manpage: Embperl::Object - Extents Embperl for building whole website with reusable components and

Provided by: libembperl-perl_2.5.0-6_amd64

NAME

       Embperl::Object - Extents Embperl for building whole website with reusable components and
       objects

SYNOPSIS

           <Location /foo>
               EMBPERL_APPNAME     unique-name
               EMBPERL_OBJECT_BASE base.htm
               EMBPERL_URIMATCH "\.htm.?|\.epl$"
               SetHandler perl-script
               PerlHandler Embperl::Object
               Options ExecCGI
           </Location>

DESCRIPTION

Embperl::Object allows you to build object-oriented (OO) websites using HTML components
which implement inheritance via subdirectories. This enables elegant architectures and
encourages code reuse. The use of inheritance also enables a website-wide "look and feel"
to be specified in a single HTML file, which is then used as a template for every other
page on the site. This template can include other modules which can be overridden in
subdirectories; even the template itself can be overridden. In a nutshell, Embperl::Object
makes the design of large websites much more intuitive, allowing object-oriented concepts
to be utilised to the fullest while staying within the "rapid application development"
model of Perl and HTML.

Embperl::Object is basicly a mod_perl handler or could be invoked offline and helps you to
build a whole page out of smaller parts. Basicly it does the following:

When a request comes in, a page, which name is specified by EMBPERL_OBJECT_BASE, is
searched in the same directory as the requested page. If the pages isn't found,
Embperl::Object walking up the directory tree until it finds the page, or it reaches
"DocumentRoot" or the directory specified by EMBPERL_OBJECT_STOPDIR.

This page is then called as frame for building the real page. Addtionaly Embperl::Object
sets the search path to contain all directories it had to walk before finding that page.
If EMBPERL_OBJECT_STOPDIR is set the path contains all directories up to the in
EMBPERL_OBJECT_STOPDIR specified one.

This frame page can now include other pages, using the "Embperl::Execute" method. Because
the search path is set by Embperl::Object the included files are searched in the
directories starting at the directory of the original request walking up thru the
directory which contains the base page. This means that you can have common files, like
header, footer etc. in the base directory and override them as necessary in the
subdirectory.

To include the original requested file, you need to call "Execute" with a '*' as filename.
To call the the same file, but in an upper directory you can use the special shortcut
"../*".

Additionally Embperl::Object sets up a inherence hierachie for you: The requested page
inherit from the base page and the base page inherit from a class which could be specified
by "EMBPERL_OBJECT_HANDLER_CLASS", or if "EMBPERL_OBJECT_HANDLER_CLASS" is not set, from
"Embperl::Req". That allows you to define methods in base page and overwrite them as
necessary in the original requested files. For this purpose a request object, which is
blessed into the package of the requested page, is given as first parameter to each page
(in $_[0]). Because this request object is a hashref, you can also use it to store
additional data, which should be available in all components. Embperl does not use this
hash itself, so you are free to store whatever you want. Methods can be ordinary Perl
sub's (defined with [! sub foo { ... } !] ) or Embperl sub's (defined with [$sub foo $]
.... [$endsub $]) .

Runtime configuration

       The runtime configuration is done by setting environment variables, in your web server's
       configuration file. Basicly the configuration is the same as for normal Embperl. All
       Embperl configuration directives also applies to Embperl::Object. There are a few
       addtional configuration directives listed below. Addtionaly you have to set the
       "PerlHandler" to "Embperl::Object" when running under mod_perl or use "epocgi.pl" instead
       of "embpcgi.pl" when running as CGI Script.

   EMBPERL_DECLINE
       Perl regex which files should be ignored by Embperl::Object

   EMBPERL_FILESMATCH
       Perl regex which files should be processed by Embperl::Object

   EMBPERL_OBJECT_BASE
       Name of the base page to search for

   EMBPERL_OBJECT_STOPDIR
       Directory where to stop searching for the base page

   EMBPERL_OBJECT_ADDPATH
       Additional directories where to search for pages. Directories are separated by ";" (on
       Unix ":" works also). This path is always appended to the searchpath.

   EMBPERL_OBJECT_FALLBACK
       If the requested file is not found the file given by "EMBPERL_OBJECT_FALLBACK" is
       displayed instead. If "EMBPERL_OBJECT_FALLBACK" isn't set a staus 404, NOT_FOUND is
       returned as usual. If the fileame given in "EMBPERL_OBJECT_FALLBACK" doesn't contain a
       path, it is searched thru the same directories as "EMBPERL_OBJECT_BASE".

   EMBPERL_OBJECT_HANDLER_CLASS
       If you specify this call the template base and the requested page inherit all methods from
       this class. This class must contain "Embperl::Req" in his @ISA array.

   EMBPERL_OBJECT_APP
       Filename of the application object. The file should contain the Perl code for the
       application object. The must be no package name given (as the package is set by
       Embperl::Object), but the @ISA should point to Embperl::App.  If set this file is searched
       through the same search path as any content file.  After a successfull load the init
       method is called with the Embperl request object as parameter. The init method can change
       the parameters inside the request object to influence the current request.

       The init method should return zero or a valid HTTP status code (e.g. return 302 and set
       the location header in %http_headers_out)

Execute

       You can use Embperl::Object also offline. You can do this by calling the function
       "Embperl::Object::Execute". "Execute" takes a hashref as argument, which can contains the
       same parameters as the "Embperl::Execute" function. Additionally you may specify the
       following parameters:

       object_base
           same as $ENV{EMBPERL_OBJECT_BASE}

       object_addpath
           same as $ENV{EMBPERL_OBJECT_ADDPATH}

       object_stopdir
           same as $ENV{EMBPERL_OBJECT_STOPDIR}

       object_fallback
           same as $ENV{EMBPERL_OBJECT_FALLBACK}

       object_handler_class
           same as $ENV{EMBPERL_OBJECT_HANDLER_CLASS}

       See also the "object" and "isa" parameters in Embperl's Execute function, on how to setup
       additional inherence and how to create Perl objects out of Embperl pages.

Basic Example

       With the following setup:

        <Location /foo>
           PerlSetEnv EMBPERL_OBJECT_BASE base.htm
           PerlSetEnv EMBPERL_FILESMATCH "\.htm.?|\.epl$"
           SetHandler perl-script
           PerlHandler Embperl::Object
           Options ExecCGI
        </Location>

       Directory Layout:

        /foo/base.htm
        /foo/head.htm
        /foo/foot.htm
        /foo/page1.htm
        /foo/sub/head.htm
        /foo/sub/page2.htm

       /foo/base.htm:

        <html>
        <head>
        <title>Example</title>
        </head>
        <body>
        [- Execute ('head.htm') -]
        [- Execute ('*') -]
        [- Execute ('foot.htm') -]
        </body>
        </html>

       /foo/head.htm:

        <h1>head from foo</h1>

       /foo/sub/head.htm:

        <h1>another head from sub</h1>

       /foo/foot.htm:

        <hr> Footer <hr>

       /foo/page1.htm:

        PAGE 1

       /foo/sub/page2.htm:

        PAGE 2

       /foo/sub/index.htm:

        Index of /foo/sub

       If you now request http://host/foo/page1.htm you will get the following page

        <html>
        <head>
        <title>Example</title>
        </head>
        <body>
        <h1>head from foo</h1>
        PAGE 1
        <hr> Footer <hr>
        </body>
        </html>

       If you now request http://host/foo/sub/page2.htm you will get the following page

        <html>
        <head>
        <title>Example</title>
        </head>
        <body>
        <h1>another head from sub</h1>
        PAGE 2
        <hr> Footer <hr>
        </body>
        </html>

       If you now request http://host/foo/sub/ you will get the following page

        <html>
        <head>
        <title>Example</title>
        </head>
        <body>
        <h1>another head from sub</h1>
        Index of /foo/sub
        <hr> Footer <hr>
        </body>
        </html>

Example for using method calls

       (Everything not given here is the same as in the example above)

       /foo/base.htm:

        [!

        sub new
           {
           my $self = shift ;

           # here we attach some data to the request object
           $self -> {fontsize} = 3 ;
           }

        # Here we give a default title
        sub title { 'Title not given' } ;

        !]

        [-

        # get the request object of the current request
        $req = shift ;

        # here we call the method new
        $req -> new ;

        -]

        <html>
        <head>
        <title>[+ $req -> title +]</title>
        </head>
        <body>
        [- Execute ('head.htm') -]
        [- Execute ('*') -]
        [- Execute ('foot.htm') -]
        </body>
        </html>

       /foo/head.htm:

        [#
           here we use the fontsize
           Note that
             $foo = $_[0]
           is the same as writing
             $foo = shift
        #]

        <font size=[+ $_[0] -> {fontsize} +]>header</font>

       /foo/sub/page2.htm:

        [!

        sub new
           {
           my $self = shift ;

           # here we overwrite the new method form base.htm
           $self -> {fontsize} = 5 ;
           }

        # Here we overwrite the default title
        sub title { 'Title form page 2' } ;

        !]

        PAGE 2

Author

       G. Richter (richter at embperl dot org)