__constructor overloading in PHP5?

Discussion in 'PHP' started by benjib98, Jan 8, 2008.

0
  1. #1
    Hi,

    just wondering how is the constructor overloading done in PHP5?As in other OOP languages you can have more constructors for a class, with different params and logic, in PHP I have seen only constructor overloading with predefined parameters like:
    class MyClass
    {
    public function __constructor($nParam1, $nParam2 = 0, $boParam3 = false)
    {
    //...some logic
    }
    }

    //so you can use a on parameter constructor or as you need
    $test1 = new MyClass(5);
    $test2 = new MyClass(5, 4);
    $test3 = new MyClass(5, 4, true);

    But how can I achieve to have a constructor with no param and another with parameter, like:
    public function __constructor()
    {
    //logic
    }
    public function __constructor($nParam)
    {
    //logic
    }

    can I do this?
    class MyTest
    {
    public function __constructor($nParam = null)
    {
    if($nParam == null)
    {
    }
    else
    {
    }
    }

    //and then
    $test4 = new MyTest();
    $test5 = new MyTest(3);

    I found a link to a code, which I am not sure about if it is valid in PHP5
    Many thanks
    Ben
    }
     
    benjib98, Jan 8, 2008 IP
  2. benjib98

    benjib98 Peon

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    #2
    benjib98, Jan 8, 2008 IP
  3. Barti1987

    Barti1987 Well-Known Member

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    #3
    You could do the above, but for organization sake, you should have two constructors instead:

    construct
    constructA

    Peace,
     
    Barti1987, Jan 8, 2008 IP
  4. benjib98

    benjib98 Peon

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    #4
    hmm...
    What do you mean by two constructors:
    construct
    constructA
    ??????????
    Can you explain it? As of my knowledge, PHP does not support Java like constructor overloading, so this is not valid:
    class MyClass
    {
    function MyClass()
    {
    }
    function MyClass($value)
    {
    print "$value";
    }
    /*nor the following:
    function __construct()
    {
    }
    function __construct($value)
    {
    print "$value";
    }
    */
    }
    $test = new MyClass();
    $otherTest = new MyClass(1);

    If I am wrong, please correct me.
    My main goal is to have a constructor with different number of parameters of different type - providing different logic, therefore the parameter names themself should be unique and not to let the developer into confusion, so the default value solution is not an ideal solution.

    btw:my post contained 'constructor' instead of 'construct' so sorry for that.
    Thanks
    Ben
     
    benjib98, Jan 8, 2008 IP
  5. InFloW

    InFloW Peon

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    #5
    PHP5 does not support object overloading in the same sense that say Java does it. You cannot do say

    
<?php
class MyClass
{
public function __construct()
{
}
public function __construct($var)
{

}

}
    PHP:
    You have two options one to set default values for the extra fields so say 

    
public function __construct($var = 5; $varb = 6;)
{

}
    PHP:
    The second option would be to create something like

    
public function __construct()
{
$num_args=func_num_args(); 
switch($num_args)
{
   case 0:
        print 'do something';
   break;
   case 1:
        $arg_one=func_get_arg(0);
        print $arg_one;
   break;

}
}
    PHP:
    Hope that helps
     
    InFloW, Jan 8, 2008 IP