Object-oriented Programming in PHP: A way to develop a large PHP project (v)

Using classes for data storage
A great thing about PHP and OOP is that you can easily define a class to manipulate something, and you can invoke the appropriate class whenever you want to use it. Suppose you have an HTML form that allows users to select a product by selecting the Product ID number. In the database has the product information, you want to display the product, show its price and so on. You have different types of products, and the same action may have different meanings for different products. For example, displaying a sound might mean playing it, but for other kinds of products it might mean displaying a picture in the database. You can use OOP or PHP to reduce coding and improve quality:

Define a product's class, define the method it should have (for example: Display), and then define the classes for each type of product, from the product class to come out (Sounditem class, Viewableitem class, etc.), covering the methods in the product class so that they act as you think.

A typical product table may have (ID, type, price, description, and so on), depending on the type of each product in the database, given the class name. Then in the processing script, you can remove the type value from the database and instantiate an object named type:

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$obj =new $type ();
$obj->action ();

?>--------------------------------------------------------------------------------
This is a very good feature of PHP, you can not consider the type of object, call $obj display method or other methods. Use
This technique, you don't need to modify the script to add a new type of object, just add a class that handles it.

This is a powerful feature, as long as you define the method without considering the types of all the objects, implement them in different ways, and then use them in the main script for any object, no if...else, no two programmers, only happy.

Now do you agree that programming is easy, maintenance is cheap, reusable is true?

If you manage a group of programmers, assigning jobs is easy, and everyone can be responsible for one type of object and the class that handles it.

Internationalization can be achieved through this technology, according to the user's chosen language field to apply the corresponding class can be, and so on.


Copy and Clone
When you create a $obj object, you can copy the object through the $obj2= $obj, and the new object is a copy of the $obj (not a
A reference), so it has the $obj state at the time. Sometimes, you don't want to do this, you just want to create a new one like the Obj class
object, you can invoke the constructor of the class by using the new statement. It can also be implemented in PHP by serialization, and a base class, but the
Some other classes are derived from the base class.



Enter hazardous areas
When you serialize an object, you get a string of some format, and if you're interested, you can tune it, where the string has
The name of the class (great!) ), you can take it out, like this:

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$herring =serialize ($obj);
$vec =explode (': ', $herring);
$nam =str_replace ("\" "," ', $vec [2]);

?>--------------------------------------------------------------------------------
So suppose you create a "Universe" class and force all classes to be extended from Universe, you can Universe
A clone method is defined in the following:
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Class Universe {
function Clone () {
$herring =serialize ($this);
$vec =explode (': ', $herring);
$nam =str_replace ("\" "," ', $vec [2]);
$ret =new $nam;
return $ret;
}
}

And then
$obj =new Something ();

Extending from Universe
$other = $obj->clone ();

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What you get is a new object of the Something class, which is the same as using the new method, which calls the constructor to create the object. I don't know if this is useful for you, but the Universe class can know the name of the derived class as a good experience. Imagination is the only limit.

Note: I use PHP4, I write some things under PHP3 may not work.


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