Re: RedBlackTree thin wrapper initialization

[Chris via Digitalmars-d]

On Wednesday, 28 May 2014 at 08:49:42 UTC, Rene Zwanenburg wrote:
On Wednesday, 28 May 2014 at 08:37:14 UTC, Chris wrote:
On Wednesday, 28 May 2014 at 07:13:37 UTC, BlackEdder wrote:
I'm trying to write a thin wrapper around redblacktree, but 
it seems every object of the class shares the same copy of 
redblacktree. Am I doing something wrong or is this a bug.

Minimal code example:

import std.array;
import std.container;
import std.stdio;

class A {
  auto tree = new RedBlackTree!string();
}

unittest {
  auto a = new A();
  a.tree.insert( "a" );
  auto b = new A();
  writeln( "Should be empty, but is: ", b.tree.array );
  writeln( "Should be empty, but has length: ", b.tree.length 
);
}

Which results in the following output:
$ rdmd -unittest rbt.d
Should be empty, but is: ["a"]
Should be empty, but has length: 1


I'm using dmd 2.0.65.

Have you tried

class A {
 RedBlackTree!(string) tree;
 this() {
   tree = new RedBlackTree!string();
 }
}

Maybe in your implementation all instances of class A share 
the same underlying instance RedBlackTree, or class 
RedBlackTree was designed as a singleton (which would seem odd 
to me).

PS This question would be better suited for the "D learn" 
forum.

Ninja'd ;)

Also, if you want to avoid repeating long type names an alias 
can help:

class A
{
  alias TreeType = RedBlackTree!string;

  TreeType tree;

  // etc etc.
}

In this case it isn't too bad but some template instantiations 
can get fairly long.

Tell me about it, I'm in the process of alias'ing my template 
types, cos I've really long type instantiations now like

type = Type!(Type2!(Type3!(int, string), string))();