Php design mode Decorator)

Dynamically add some additional responsibilities to an object, which is more flexible in terms of the extension function than the subclass generation method. Copy codeThe code is as follows:
/**
* Decoration mode
*
* Dynamically add some additional responsibilities to an object, which is more flexible in terms of the extension function than the subclass generation method.
*/
Header ("Content-type: text/html; charset = utf-8 ");
Abstract class MessageBoardHandler
{
Public function _ construct (){}
Abstract public function filter ($ msg );
}

Class MessageBoard extends MessageBoardHandler
{
Public function filter ($ msg)
{
Return "process the content on the message board |". $ msg;
}
}

$ Obj = new MessageBoard ();
Echo $ obj-> filter ("You must learn the decoration mode well.
");

// --- The following is the decoration mode ----
Class MessageBoardDecorator extends MessageBoardHandler
{
Private $ _ handler = null;

Public function _ construct ($ handler)
{
Parent: :__ construct ();
$ This-> _ handler = $ handler;
}

Public function filter ($ msg)
{
Return $ this-> _ handler-> filter ($ msg );
}
}

// Filter html
Class HtmlFilter extends MessageBoardDecorator
{
Public function _ construct ($ handler)
{
Parent: :__ construct ($ handler );
}

Public function filter ($ msg)
{
Return "filter out HTML tags |". parent: filter ($ msg); // filter out HTML tags. in this case, only text is added and not processed.
}
}

// Filter sensitive words
Class SensitiveFilter extends MessageBoardDecorator
{
Public function _ construct ($ handler)
{
Parent: :__ construct ($ handler );
}

Public function filter ($ msg)
{
Return "filter out sensitive words |". parent: filter ($ msg); // filter out sensitive words. at this time, only a text is added and not processed.
}
}

$ Obj = new HtmlFilter (new SensitiveFilter (new MessageBoard ()));
Echo $ obj-> filter ("Be sure to learn the decoration mode!
");