Zephir\Variable::isReadOnly PHP Method

    public function isReadOnly()
    {
        return $this->readOnly;
    }

 /**
  * Compiles x--
  *
  * @param string $variable
  * @param ZephirVariable $symbolVariable
  * @param CompilationContext $compilationContext
  * @param array $statement
  */
 public function assign($variable, ZephirVariable $symbolVariable, CompilationContext $compilationContext, $statement)
 {
     if (!$symbolVariable->isInitialized()) {
         throw new CompilerException("Cannot mutate variable '" . $variable . "' because it is not initialized", $statement);
     }
     if ($symbolVariable->isReadOnly()) {
         throw new CompilerException("Cannot mutate variable '" . $variable . "' because it is read only", $statement);
     }
     $codePrinter = $compilationContext->codePrinter;
     switch ($symbolVariable->getType()) {
         case 'int':
         case 'uint':
         case 'long':
         case 'ulong':
         case 'double':
         case 'char':
         case 'uchar':
             $codePrinter->output($variable . '--;');
             break;
         case 'variable':
             /**
              * Variable is probably not initialized here
              */
             if ($symbolVariable->hasAnyDynamicType('unknown')) {
                 throw new CompilerException("Attempt to increment uninitialized variable", $statement);
             }
             /**
              * Decrement non-numeric variables could be expensive
              */
             if (!$symbolVariable->hasAnyDynamicType(array('undefined', 'int', 'long', 'double', 'uint'))) {
                 $compilationContext->logger->warning('Possible attempt to decrement non-numeric dynamic variable', 'non-valid-decrement', $statement);
             }
             $compilationContext->headersManager->add('kernel/operators');
             if ($symbolVariable->isLocalOnly()) {
                 $codePrinter->output('zephir_decrement(&' . $variable . ');');
             } else {
                 $symbolVariable->separate($compilationContext);
                 $codePrinter->output('zephir_decrement(' . $variable . ');');
             }
             break;
         default:
             throw new CompilerException("Cannot decrement variable: " . $symbolVariable->getType(), $statement);
     }
 }