我在网上找到了这段代码，它在过程中有一个过程。我不明白为什么作者会选择这样写。我注意到的是执行了一个递归函数。

为什么他不像我见过的大多数代码那样将程序分开。

他的实施：

procedure XML2Form(tree : TJvPageListTreeView; XMLDoc : TXMLDocument);
var
  iNode : IXMLNode;

  procedure ProcessNode(
    Node : IXMLNode; 
    tn   : TTreeNode);
  var
    cNode : IXMLNode;
  begin
    if Node = nil then Exit;
    with Node do
    begin
      tn := tree.Items.AddChild(tn, Attributes['text']);
      tn.ImageIndex := Integer(Attributes['imageIndex']);
      tn.StateIndex := Integer(Attributes['stateIndex']);
    end;

    cNode := Node.ChildNodes.First;
    while cNode <> nil do
    begin
      ProcessNode(cNode, tn);
      cNode := cNode.NextSibling;
    end;
  end; (*ProcessNode*) 
begin
  tree.Items.Clear;
  XMLDoc.FileName := ChangeFileExt(ParamStr(0),'.XML');
  XMLDoc.Active := True;

  iNode := XMLDoc.DocumentElement.ChildNodes.First;

  while iNode <> nil do
  begin
    ProcessNode(iNode,nil);
    iNode := iNode.NextSibling;
  end;
  XMLDoc.Active := False;
end; (* XML2Form *)

procedure Form2XML(tree: TJVPageListTreeView);
var
  tn : TTreeNode;
  XMLDoc : TXMLDocument;
  iNode : IXMLNode;

  procedure ProcessTreeItem(
    tn    : TTreeNode;
    iNode : IXMLNode);
  var
    cNode : IXMLNode;
  begin
    if (tn = nil) then Exit;
    cNode := iNode.AddChild('item');
    cNode.Attributes['text'] := tn.Text;
    cNode.Attributes['imageIndex'] := tn.ImageIndex;
    cNode.Attributes['stateIndex'] := tn.StateIndex;
    cNode.Attributes['selectedIndex'] := tn.SelectedIndex;

    //child nodes
    tn := tn.getFirstChild;
    while tn <> nil do
    begin
      ProcessTreeItem(tn, cNode);
      tn := tn.getNextSibling;
    end;
  end; (*ProcessTreeItem*)
begin
  XMLDoc := TXMLDocument.Create(nil);
  XMLDoc.Active := True;
  iNode := XMLDoc.AddChild('tree2xml');
  iNode.Attributes['app'] := ParamStr(0);

  tn := tree.TopItem;
  while tn <> nil do
  begin
    ProcessTreeItem (tn, iNode);

    tn := tn.getNextSibling;
  end;

  XMLDoc.SaveToFile(ChangeFileExt(ParamStr(0),'.XML'));
  XMLDoc := nil;
end; (* Form2XML *)

或修改后的实施：

procedure ProcessNode(Node : IXMLNode; tn : TTreeNode);
var
  cNode : IXMLNode;
begin
  if Node = nil then Exit;
  with Node do
  begin
    tn := tree.Items.AddChild(tn, Attributes['text']);
    tn.ImageIndex := Integer(Attributes['imageIndex']);
    tn.StateIndex := Integer(Attributes['stateIndex']);
  end;

  cNode := Node.ChildNodes.First;
  while cNode <> nil do
  begin
    ProcessNode(cNode, tn);
    cNode := cNode.NextSibling;
  end;
end; (*ProcessNode*)

procedure ProcessTreeItem(tn : TTreeNode; iNode : IXMLNode);
var
  cNode : IXMLNode;
begin
  if (tn = nil) then Exit;
  cNode := iNode.AddChild('item');
  cNode.Attributes['text'] := tn.Text;
  cNode.Attributes['imageIndex'] := tn.ImageIndex;
  cNode.Attributes['stateIndex'] := tn.StateIndex;
  cNode.Attributes['selectedIndex'] := tn.SelectedIndex;

  //child nodes
  tn := tn.getFirstChild;
  while tn <> nil do
  begin
    ProcessTreeItem(tn, cNode);
    tn := tn.getNextSibling;
  end;
end; (*ProcessTreeItem*)

procedure XML2Form(tree : TJvPageListTreeView; XMLDoc : TXMLDocument);
var
  iNode : IXMLNode;
begin
  tree.Items.Clear;
  XMLDoc.FileName := ChangeFileExt(ParamStr(0),'.XML');
  XMLDoc.Active := True;

  iNode := XMLDoc.DocumentElement.ChildNodes.First;

  while iNode <> nil do
  begin
    ProcessNode(iNode,nil);
    iNode := iNode.NextSibling;
  end;
  XMLDoc.Active := False;
end;

procedure Form2XML(tree: TJVPageListTreeView);
var
  tn : TTreeNode;
  XMLDoc : TXMLDocument;
  iNode : IXMLNode;
begin
  XMLDoc := TXMLDocument.Create(nil);
  XMLDoc.Active := True;
  iNode := XMLDoc.AddChild('tree2xml');
  iNode.Attributes['app'] := ParamStr(0);

  tn := tree.TopItem;
  while tn <> nil do
  begin
    ProcessTreeItem (tn, iNode);

    tn := tn.getNextSibling;
  end;

  XMLDoc.SaveToFile(ChangeFileExt(ParamStr(0),'.XML'));
  XMLDoc := nil;
end; (* Form2XML *)