Search code examples
phpmagic-constants

Best practices for usage of PHP’s Magic Constants

What are the best practices for usage of PHP’s Magic Constants, such as __LINE__ , __FILE__, __FUNCTION__, __CLASS__ and __METHOD__?

For example I use __LINE__ and __CLASS__ to locate the SQL Error like this :

$result = mysql_query($query)
or die("Error SQL line ".__LINE__ ." class ".__CLASS__." : ".mysql_error());

Is this an acceptable practice?

Solution

  • The practice you show has two shortcomings:

    • You are not showing the file the error occurs in - you'd have to have a very strict file structure that maps classes to files 1:1 for this to be useful

    • __CLASS__ will show you the wrong result if the error occurs in an inherited class. Use get_class($this) to get the actual current class.

    Other than that, using these constants is perfectly acceptable. Note that

    • __FUNCTION__ and __CLASS__ were added in PHP 4.3

    • __METHOD__ is available since PHP 5.0.0

    • __DIR__ and __NAMESPACE__ are available since PHP 5.3.

    docs