Question

Is there a way to have a function return a editable reference to some internal data. Here’s an example I hope helps show what I mean.

class foo {     public int value; }  class bar {     bar()     {        m_foo = new foo();        m_foo.value = 42;     }     private m_foo;     foo getFoo(){return m_foo;} }  class main {     int main()     {         bar b = new bar();         b.getFoo().value = 37;     } } 

The return of getFoo() according to ‘==’ is the same as the internal m_foo until I try to edit it. In c/c++ I’d return a reference or pointer.

Answer 1

Actually, your code sample, after some cleaning up, does demonstrate that when you assign 37 to value, you are changing bar’s interman m_foo too. So the answer is, your function is returning a reference type. Now, maybe your real code is different, and it’s returning not an reference type but an int, a value type, or string, a kind of special beastie…

using System;  namespace ConsoleApplication1 {     public class foo     {         public int value;     };      public class bar     {         public bar()         {             m_foo = new foo();             m_foo.value = 42;         }          private foo m_foo;         public foo getFoo() { return m_foo; }     };      public class Program     {         public static int Main()         {             bar b = new bar();             b.getFoo().value = 37;             return 0;         }     }; } 

More about reference vs value types: http://www.albahari.com/valuevsreftypes.aspx