Re: TTree::GetEvent without creating new objects?

Robert Casties (casties@mail.desy.de)
Thu, 30 Oct 1997 17:13:01 +0100 (CET)


Hi Rene!

On Thu, 30 Oct 1997, Rene Brun wrote:

> When you use the non-split mode, GetEvent will automatically
> -delete the object (event) at the address specified in SetBranchAddress
> - create a new instance via the default constructor
> - fill the event via Streamer.
>
> In split-mode, the original event object is kept (no need to delete it
> and rebuilt it). Only sub-objects need to be rebuilt.

That would be what I wanted but how to do...

> I strongly encourage you to use the automatic split method.
> It has only advantages. This, however, implies some thinking
> on the top level event model to take advantage of the possibility
> to read only subsets of one event.

..since the automatic splitting does not work (AFAIK) on objects
containing pointers to simple types.

I have a raw data object containing variable length byte arrays. I wanted
to allocate the maximum space before and then only copy every event into
that space. (I didn't want to use TArray -- seems sorta overkill)

Cheers
Robert