Accessing a field of a containing class from within a nested class

[Ali Çehreli via Digitalmars-d-learn]

On 04/01/2015 11:25 AM, Charles Hixson via Digitalmars-d-learn wrote:> 
The class Node is contained within the struct BTree.
 > The field   btFile is contained within the struct BTree.
 > The statement is within a function within the Node class.
 >
 > I've tried many variations, here are a few:
 >
 > btFile.write(self.nodeId, cast(void*)&(self));
 > results in:
 > need 'this' for 'btFile' of type 'BlockFile'
 >
 > this.btFile.write(self.nodeId, cast(void*)&(self));
 > results in:
 > Error: no property 'btFile' for type 'btplus.BTree.Node'
 >
 > this.BTree.btFile.write(self.nodeId, cast(void*)&(self));
 > results in:
 >   Error: constructor btplus.BTree.this (string fName) is not callable
 > using argument types (Node)
 >
 > Perhaps BTree needs to be a class?  I made it a struct because I want it
 > to definitely close properly when it
 > goes out of scope.

Can you modify the definition of Node? If so, perhaps it's possible 
construct Node objects with a reference to its btFile:

import std.stdio;

class Node
{
     int *btFile;

     this(int *btFile)
     {
         this.btFile = btFile;
     }

     void foo()
     {
         writeln(*btFile);
     }
}

struct BTree
{
     int btFile;
     Node node;

     this(int btFile)
     {
         this.btFile = btFile;
         this.node = new Node(&this.btFile);
     }
}

void main()
{
     auto bt = BTree(42);
     bt.node.foo();
}

Ali