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)
See Also¶
perl(1), Embperl, mod_perl, Apache httpd