Best practice to do nested TRY / FINALLY statement

Question

Hi What is the best way to do nested try & finally statements in delphi?

var cds1  : TClientDataSet;
    cds2  : TClientDataSet;
    cds3  : TClientDataS         


        

Answer 1

@mghie: Delphi has got stack allocated objects:

type
  TMyObject = object
  private
    FSomeField: PInteger;
  public
    constructor Init;
    destructor Done; override;
  end;

constructor TMyObject.Init;
begin
  inherited Init;
  New(FSomeField);
end;

destructor TMyObject.Done;
begin
  Dispose(FSomeField);
  inherited Done;
end;

var
  MyObject: TMyObject;

begin
  MyObject.Init;
  /// ...
end;

Unfortunately, as the above example shows: Stack allocated objects do not prevent memory leaks.

So this would still require a call to the destructor like this:

var
  MyObject: TMyObject;

begin
  MyObject.Init;
  try
    /// ...
  finally
    MyObject.Done;
  end;
end;

OK, I admit it, this is very nearly off topic, but I thought it might be interesting in this context since stack allocated objects were mentioned as a solution (which they are not if there is no automatic destructor call).