How to delay a shell command in delphi?

Question

Hi all

I am working with Delphi 2010 and the ShellAPI. I need a little help as the program I am building grows. Here is the jest of the application:

Checks to see if a certain condition exists If said condition exists it begins to execute 2 shell commands which are dependent on the previous one executing

   uses
  ShellApi;

procedure RenameDir(DirFrom, DirTo: string);
var
  shellinfo: TSHFileOpStruct;
begin
  with shellinfo do
  begin
    Wnd    := 0;
    wFunc  := FO_RENAME;
    pFrom  := PChar(DirFrom);
    pTo    := PChar(DirTo);
    fFlags := FOF_FILESONLY or FOF_ALLOWUNDO or
              FOF_SILENT or FOF_NOCONFIRMATION;
  end;
  SHFileOperation(shellinfo);
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
  RenameDir('C:\Dir1', 'C:\Dir2');

  RenameDir('C:\Dir3', 'C:\Dir');


end;

I am a novice at Delphi but I can see the issue, the second command is executing before the previous command completes. How do I solve this issue so that the first command executes and finishes before the second one is called?

UPDATE: I added the full pseudo code so that it shows what I attempting to do.

Answer 1

Two simple ways to do this:

1. Insert a Sleep(X); command between the two and fill in the x with something low like 5 or 10 (should be all the ms you need).
2. Insert an Application.ProcessMessages command between the two to allow other events including the renaming to complete.

Answer 2

If the command you use is external command/program, consider use CreateProcess() and passing INFINITE to WaitForSingleObject(). Look at the ExecAndWait() example here.

Answer 3

Maybe you could use SHChangeNotifyRegister() to be notified when the directory name is actually changed.