[fpc-pascal] Forward declarations

[Mattias Gaertner]

On Thu, 22 Dec 2011 15:33:13 -0500
Timothy Groves <the.tail.kinker at gmail.com> wrote:

> Can anyone think of a situation in which you would *have* to use forward 
> declared functions?  I'm trying to come up with an example for such for 
> my book, and I am drawing a blank.

Traverse a html tree. For example with div and p nodes. Both div and
p nodes can have children that are div and p nodes.

procedure Proc(RootNode: TNode);

  procedure ReadChildrenv(Node: TNode); forward;

  procedure ReadP(Node: TNode);
  begin
    ...
    ReadChildren(Node);
  end;

  procedure ReadDiv(Node: TNode);
  begin
    ...
    ReadChildren(Node);
  end;

  procedure ReadChildren(Node: TNode);
  begin
    for Child in Node do begin
      if Child is Div then ReadDiv(Child)
      else if Child is P then ReadP(Child);
    end;
  end;

begin
  ReadChildren(RootNode);
end;

Mattias