detect if function exists within the class and if not call a different function. PHP

Question

I know there are other ways around this but just for the sake of simplicity I would like to know if its possible to do something like:

   MyFactory::Create()->callMe();

and myFactory class:

   class MyFactory {
       private $obj;

       public static Create() { 
           $this->obj = new ClassA();
           return $this->obj;
       }

       public function __undefinedFunctionCall() {
           //function does not exist within MyFactory Class but it exists
           // in ClassA
           $this->obj->callMe();
       }
   }

so basically the function callMe does not exist within MyFactory class but it exists in ClassA. Dont ask me why I cant just extend classA because the code structure is already written and its not up to me to modify it. I just need a way around it.

I think thats it inside __call I could check if function exists and if not try the function from other class. thanks Mark — GGio
– GGio, Commented Sep 4, 2013 at 16:34

Avag Sargsyan · Accepted Answer · 2017-08-28 14:00:05Z

5

You could simply use method_exists

It takes 2 parameters method_exists ( mixed $object, string $method_name )

The first is an object instance or a class name, and the second is The method name.

So it should be as simple as:

if(method_exists($this->obj,'callMe')){
   $this->obj->callMe();
}
else{
//...throw error do some logic
}

edited Aug 28, 2017 at 14:00

Avag Sargsyan

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answered Sep 4, 2013 at 16:38

Stephan

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1 Comment

GGio Over a year ago

as I mentioned i do not want to do this check outside of class. Want my Factory class to detect any undefined function calls

GGio · Accepted Answer · 2013-09-04 16:45:41Z

1

Thanks to Mark Baker I found the solution. In case anyone else has similar problem the following solved it:

added this function inside my factory class

    public function __call($name, $arguments)
    {
            //if function exists within this class call it
        if (method_exists(self, $name))
        {
            $this->$name($arguments);
        }
        else
        {
            //otherwise check if function exists in obj and call it
            if (method_exists($this->obj, $name))
            {
                $this->obj->$name($arguments);
            }
            else 
            {
                throw new \Exception('Undefined function call.');
            }          
        }
    }

answered Sep 4, 2013 at 16:45

GGio

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1 Comment

Vahid Hallaji Over a year ago

Also notice that you can not use $this inside static Create method as you wrote in the question.

Vahid Hallaji · Accepted Answer · 2013-09-04 16:36:06Z

0

To checks if the class method exists or not:

$this->obj = new ClassA();
var_dump(method_exists($this->obj,'callMe'));

if it is static method:

var_dump(method_exists('ClassA','callMe'));

Returns true if the method given by method_name has been defined for the given object, false otherwise.

php.net manual

answered Sep 4, 2013 at 16:36

Vahid Hallaji

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1 Comment

GGio Over a year ago

that I know but I want to detect it within class inside MyFactory and not outside of it.

Nathan · Accepted Answer · 2014-04-23 22:01:27Z

Your correct about using the Magic method __call(), but you are implementing it wrong.

You dont need to check if it exists on its own class, PHP does this internally for you. The magic method __call only happens if the method doesn't exist.
You are passing a single array argument to $this->obj->$name, where you should be passing in each argument separately.
Nothing gets returned.

This is how you should implement the __call magic method for your purpose.

public function __call($name, $arguments) {
    if(method_exists($this->obj,$name)) {
        return call_user_func_array(array($this->obj, $name), $arguments);
    } else {
        throw new Exception("Undefined method ".get_class($this)."::".$name);
    }
}

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