AcquireExceptionObject() / ReleaseExceptionObject()

[Der schöne Günther]

Ich bin jetzt ein bisschen baff

Wenn ich möchte dass eine Exception über ihren try..except -Block hinaus lebt gibt es zwei Routinen AcquireExceptionObject() und ReleaseExceptionObject().

Schaut man in den interface-Teil von System.pas:

Zitat:

{
When an exception is thrown, the exception object that is thrown is destroyed
automatically when the except clause which handles the exception is exited.
There are some cases in which an application may wish to acquire the thrown
object and keep it alive after the except clause is exited. For this purpose,
we have added the AcquireExceptionObject and ReleaseExceptionObject functions.
These functions maintain a reference count on the most current exception object,
allowing applications to legitimately obtain references. If the reference count
for an exception that is being thrown is positive when the except clause is exited,
then the thrown object is not destroyed by the RTL, but assumed to be in control
of the application. It is then the application's responsibility to destroy the
thrown object. If the reference count is zero, then the RTL will destroy the
thrown object when the except clause is exited.
}
function AcquireExceptionObject: Pointer;
procedure ReleaseExceptionObject;

Schaut man in den implementation-Teil dann gibt es ReleaseExceptionObject() zwei mal:

Delphi-Quellcode:

procedure ReleaseExceptionObject;
begin
end;

und

Delphi-Quellcode:

procedure ReleaseExceptionObject;
asm
{$IFDEF ALIGN_STACK}
        SUB     ESP, 12
{$ENDIF ALIGN_STACK}
        CALL    CurrentException
{$IFDEF ALIGN_STACK}
        ADD     ESP, 12
{$ENDIF ALIGN_STACK}
        OR      EAX, EAX
        JE      @@Error
        CMP     [EAX].TRaisedException.RefCount, 0
        JE      @@Error
        DEC     [EAX].TRaisedException.RefCount
        RET
@@Error:
{ This happens if there is no exception pending, or
  if the reference count on a pending exception is
  zero. }
        JMP   _Run0Error
end;

Aufgerufen wird natürlich ersteres. Heißt: Nichts passiert, die Exception verbleibt auf ewig im Speicher.

Kann mir jemand den Sinn dahinter erklären? wtf...