This code does not look right to me:

function registerAutoloadFunctions( $functionDefinition )
{
[...]
$functionNamesFunction = $functionDefinition['function_names_function'];
if ( !function_exists( $functionNamesFunction ) )

{ $this->error( 'registerFunctions', "Cannot register function definition, missing function names function '$functionNamesFunction'" ); return; }

$functionNames = $operatorNamesFunction();
[...]
shouldn't that last line read
$functionNames = $functionNamesFunction();

?

-Erlend