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Get class constant names in php?

I have a php class with some class constants that indicate the status of the instance.

When I use the class, after running some methods, I do some checks to make sure the status is what I expect.

For example, after calling some methods, I expect the status to be MEANINGFUL_STATUS_NAME

.

$objInstance->method1();
$objInstance->method2();
if ( $objInstance->status !==  class::MEANINGFUL_STATUS_NAME ) { 
    throw new Exception("Status is wrong, should not be " . class::MEANINGFUL_STATUS_NAME . ".");
}

However this gives me an exception message

"Status is wrong, should not be 2"

when i really want to see

"Status is wrong, should not be MEANINGFUL_STATUS_NAME"

So, I lost the meaning of the permanent name. I was thinking about creating an array "translation table" so I can take constant values ​​and translate them back into their name, but that seems cumbersome. How do I translate this back so I get an error that gives me a better idea of ​​what went wrong?

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3 answers


Now it seems to me that I can use strings as values ​​for constants. I'm used to seeing numbers. Is there a reason I shouldn't be doing this, or why it won't work?



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This is a rather tricky solution:



$r = new ReflectionClass("YourClassName");
$constantNames = array_flip($r->getConstants());

$objInstance->method1();   
$objInstance->method2();   
if ( $objInstance->status !== YourClassName::MEANINGFUL_STATUS_NAME ) {    
    throw new Exception("Status is wrong, should not be " . $constantNames[YourClassName::MEANINGFUL_STATUS_NAME] . ".");   
}
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Another way is to let the object check if the status is in the desired mode.

If it is not, the object's method may throw an exception.

Unadorned example:

class Klasse
{
    const WANTED_VALUE    =  1;
    const UNWANTED_VALUE  =  2;

    private static $constant_names  =  array();
    p... function __construct ()
    {
        if ( empty( self::$constant_names ) )
        {
            $class            =  new ReflectionClass( __CLASS__ );
            $constants        =  $class->getConstants();
            $constants        =  array_flip( $constants );// requires the constant values to be unique
            self::$constants  =  $constants;
        }
    }
    public function checkNeededStatus ()
    {
        $needed_status  =  self::WANTED_VALUE;// could also be a parameter(an argument) with a default value
        if ( $this->status !== $needed_status )
        {
            $constant_name  =  self::$constants[ $this->status ];
            $message        =  'Status is wrong, '
                . 'should not be: `' . $constant_name . '`.'
            ;
            //$message .=  '(it should be `' . self::$constants[ $needed_status ] . '`)';
            throw new Exception( $message );
        }
    }
}

$objInstance  =  new Klasse();
$objInstance->method1();
$objInstance->method2();
$objInstance->checkNeededStatus();

credit:

It might be a good idea to consider using Reflection. As the thrown message remains within the class, it becomes more likely to occur without losing significant maintainability.

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