note 71040 deleted from language.oop5 by colder

Note Submitter: phaxius ---- Thanks for the tip Dave, that is a much simpler way to the same functionality. One thing I noticed is that if you want to validate the arguments passed to __construct() but also are using "$this->Args = func_get_args();" to define the class members then you get all or none of the arguments stored as members after validation. For an example, a class that stores a list of numbers may require validation of the arguments to ensure that they are actually numbers before storing this in the object. Using "$this->Arg = func_get_args();" you could write something like: <?php class numbers { public function __construct(){ if(func_num_args()>=1){ // if there is at least one argument for($i=0; $i<func_num_args(); $i++) { // validation loop if(!is_numeric(func_get_arg($i))){ // if not a number echo 'Invalid argument <br />'; // complain // return false; // keeps _construct() from defining } // object members } $this->Arg=func_get_args(); // defines object members } else {die('No arguments passed');} // stops if nothing is } // passed to _construct() public function addNums(){ $sum = 0; // place to store the sum, initialized to 0 foreach($this->Arg as $number){ // addition loop $sum = $sum + $number; // add the previous sum with the } // value of the current position in the array return $sum; // returns the final sum } public function __destruct(){} } $numbers= new numbers(2.3, 7, 62, 3.75, 82, 3, 'n'); foreach($numbers->Arg as $number){ echo $number . '<br />'; } echo $numbers->addNums() . '<br />'; ?> which would output: Invalid argument 2.3 7 62 3.75 82 3 n 160.05 Although the sum is correct in this case, the storage of invalid data can cause issues on more complex code, such as if you pass objects in the construction of other objects. If the argument turns out to be an invalid object, and it stores it anyways, some functions involving members of that object will malfunction later. An example of what might happen can be seen if you uncomment the line of code that says "return false;", which would then output: Invalid argument Warning: Invalid argument supplied for foreach() in path\filename.php on line 27 Warning: Invalid argument supplied for foreach() in path\filename.php on line 18 0 In this case it results from a lack of member definition within the numbers class itself, but if something is supposed to be an object of a specific type and it is improperly validated then similar messages would result from trying to access the members of that object since it doesn't exist. As an alternative, one may wish to instead assign default values if something doesn't check out right. That way you can still use the information provided without causing error messages if something is input incorrectly. The code for the alternative constructor could look like: public function __construct(){ if(func_num_args()>=1){ // if there is at least one argument for($i=0; $i<func_num_args(); $i++){ // validation loop if(is_numeric(func_get_arg($i))){ // if the arg is numeric $nums[$i]=func_get_arg($i); // store it in $nums[$i] } else {$nums[$i]=0;} // otherwise set to default $this->Arg[$i]=$nums[$i]; // defines the object members } } else {die('No arguments passed');} // stops if nothing is } // passed to _construct() which if used would output: 2.3 7 62 3.75 82 3 0 160.05 The invalid data type was set to a default value that is the correct type. One could also add code to clean it up so that it never shows up in the final object.