polymorphism?

[Gasolene]

i want 2 different objects created using the same definition based on parameters.. ie:

$myobject = new Animal( 'dog' );
$myotherobject = new Animal( 'cat' );

// i now have to instances of same object

echo $myobject->getNoise(); // will output "mew"
echo $myotherobject->getNoise(); // will output "bark" 

right now, i just have a switch statement in the getNoise method based on the parameter in the constructor, but is it possible to keep 2 seperate object definitions using the same declaration?

php v 4.3.9

[Daimaju]

why don't you use sth. like

class Animal{
function getNoise()
{
     die('Implement in child class!');
}
}

class Cat extends Animal{

function getNoise()
{
    return 'mew';
}
} 

[Gasolene]

i know about inheritance, but i was wondering if this can be done using the "same" class name.

[dbevfat]

any particular reason why?

Inheritance provides you with just the right mechanism - those switch statements cry for decoupling

[arborint]

What you want is called the Factory pattern. There are many ways to implement it. Here is using a simple switch:

class Animal{
function Animal($type) {
     switch($type) {
    case 'cat':
        return new Cat();
        break;
    case 'dog':
        return new Dog();
        break;
    }
}
}

class Cat {

function getNoise()
{
    return 'mew';
}
}

class Dog {

function getNoise()
{
    return 'woof';
}
} 

[Gasolene]

thnx, i'll give that a try


reaon is, I have a connection object, the idea is to have 1 object that will connect to various data sources (mysql,csv,oracle,ect...).

I want the same object used for all sources, but the object is getting ery large and full of if statements. i thought there might be a way to seperate the code for each data source without having multiple objects.

ex: $db = new DAO_Connection( 'source=mysql', $moreoptions... )
or
$db = new DAO_Connection( 'source=text', $moreoptions... )

$rs = $db->open( 'select * from table' );

while( !$rs->eof() )
{
ect...

[dbevfat]

I see. Factory pattern, as previosly suggested, is probably the most suitable, but you definetly need a class tree for it. Avoid having such case and if statement in classes.

[arborint]

I want the same object used for all sources, but the object is getting ery large and full of if statements. i thought there might be a way to seperate the code for each data source without having multiple objects.

This is the same thing that PEAR DB and others do. I have never found the utility of a Factory for this. Maybe because I don't see the practical difference between the following, and the Factory requires more code and two includes:

$db = new DAO_Connection( 'source=mysql', $moreoptions... );
// and

$db = new DAO_Connection_Mysql($moreoptions... ); 

As long as the DB objects have the same interface, you can pass a DAO_Connection_Mysql or a DAO_Connection_Oracle and your code will work.

[Gasolene]

yes, there is no programmitic benifit, i just prefered having 1 object for all connections.

this way I can store the connection string in a config file, and change it that way instead of changing all object names from ...Obj_MySql to ..Obj_Oracle...

also in that actual object, the connection type and options are sent in 1 parameter.