Returning reference to a member variable

You can 'hand over' a variable by reference:

void func( double &var ){..}

But I think you know it.

1. Return Operator - MQL4 Documentation What can be returned: simple types, simple structures, object pointers.
   

2. //+------------------------------------------------------------------+
   //| Mql4 is like C++ except: no typedefs or namespaces, no pointers  |
   //| to POD, no operator(), operator*, or operator->, no implicit     |
   //| conversions (operator bool), no templated classes, no Koenig     |
   //| lookup, can't return references, no dynamic cast, no exceptions, |
   //| no class friends, no multiple inheritance. Can't use template    |
   //| <class X...> must be template <typename x...>. f(const T&){}     |
   //| f(123) or f( f2() ) doesn't compile (Build 765.) Must have a     |
   //| actual variable. Structures must be passed by reference.         |
   //+------------------------------------------------------------------+