I have an idea of using this syntax in php. It illustrates that there are different fallback ways to create an object
function __construct() {
if(some_case())
$this = method1();
else
$this = method2();
}
Is this a nightmare? Or it works?
Or it works?
It doesn't work. You can't unset or fundamentally alter the object that is being created in the constructor. You can also not set a return value. All you can do is set the object's properties.
One way to get around this is having a separate "factory" class or function, that checks the condition and returns a new instance of the correct object like so:
function factory() {
if(some_case())
return new class1();
else
return new class2();
}
See also:
Why not to do something more common like:
function __construct() {
if(some_case())
$this->construct1();
else
$this->construct2();
}
You can just create class methods method1 and method2 and just write
function __construct() {
if(some_case())
$this->method1();
else
$this->method2();
}
You can make factory method.
Example:
class A {}
class B {}
class C {
function static getObject() {
if(some_case())
return new A();
else
return new B();
}
}
$ob = C::getObject();
See @Ivan's reply among others for the correct syntax for what it looks like you're trying to do.
However, there are is another alternative - use a static method as an alternative constructor:
class myclass {
function __construct() { /* normal setup stuff here */}
public static function AlternativeConstructor() {
$obj = new myclass; //this will run the normal __construct() code
$obj->somevar = 54; //special case in this constructor.
return $obj;
}
}
...
//this is how you would use the alternative constructor.
$myobject = myclass::AlternativeConstructor();
(note: you definitely can't use $this in a static method)
If you want to share some functions, do some like
class base{
'your class'
}
class A extends base{
'your class'
}
class B extends base{
'your class'
}
And call like
if(some_case())
$obj = new A();
else
$obj = new B();
