How can I dynamically inject code into event handlers in Delphi?

Question

For debugging / performance tests I would like to dynamically add logging code to all event handlers of components of a given type at run time.

For example, for all

Answer 1

I would try this:

TDataSetBeforeOpenStartTimeStorer = class(TObject)

constructor Create(MyDataModule : TMyDatamodule);
begin
    OldBeforeOpen := MyDatamodule.OnBeforeOpen;
    MyDatamodule.OnBeforeOpen = NewBeforeOpen;
end;

procedure NewBeforeOpen(Sender: TDataset);
begin
  StoreStartTime(Sender);
  if Assigned(OldBeforeOpen) then
    OldBeforeOpen(Sender);
end;

Attach one TDataSetBeforeOpenStartTimeStorer instance to every TDataSet and you'll have your functionality.