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Now let's look at a slightly more interesting example. When you create
Perl variables in Embperl usually, their scope is the current file;
so, they are effectively "local" to that file. When you come to split
your website up into modules, however, it quickly becomes apparent
that it is very useful to have variables which are global to the
website, i.e. shared between multiple files. To achieve this, EmbperlObject has special object which is
automatically passed to every page as it is executed. This object is
usually referred to as the "Request" object, because we get one of
these objects created for every document request that the web server
receives. This object is passed in on the stack, so you can retrieve
it using the Perl "shift" statement. This object is also automatically
destroyed after the request, so the Request object cannot be used to
store data between requests. The idea is that you can store variables
which are local to the current request, and shared between all
documents on the current website; plus, as we'll see later, we can
also use it to call object methods. For example, Let's say you set up
some variables in base.epl, and then use them in file.html: /base.epl
<HTML>
<HEAD>
<TITLE>Some title</TITLE>
</HEAD>
[-
$req = shift;
$req->{webmaster} = 'John Smith'
-]
<BODY>
[- Execute ('*') -]
</BODY>
</HTML> /file.html
[- $req = shift -]
Please send all suggestions to [+ $req->{webmaster} +]. You can see that EmbperlObject is allowing us to set up global
variables in one place, and share them throughout the website. If you
place base.epl in the root document directory, you can have any
number of other files in this and subdirectories, and they will all
get these variables whenever they are executed. No matter which file
is requested, /base.epl is executed first, and then the requested
file. You don't even need to include the requested '*' file, but the usual
case would be to do so - it would be a little odd to completely ignore
the requested file!
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