function checkName($name){ if(!is_string($name)){ self::setError('Invalid input. Input parameter must be a string'); return false; } else{ return true; } }
$file = fopen("example.txt","r"); if(!$file){ self::setError('File not found or unable to open'); }In both these examples, the self setError method is used to throw or set an error message when a certain condition is met. It is difficult to determine the package library from the given information, as the self setError method can be implemented in any PHP project or application. However, this method is frequently used in object-oriented PHP programming and can be found in various PHP libraries and frameworks.