RE: [ROOT] TVector3 and TLorentzVector

From: Dave Casper (dcasper@uci.edu)
Date: Tue Oct 10 2000 - 00:57:36 MEST


	Hi,

> TVector3 and TLorentzVector have been left unchanged since your mail
> and the discussion following it. These two classes were supposed to be in
> phase with the same classes in CLHEP. It is my understanding that the
CLHEP
> maintainers were against your proposal (from some private emails!).

Yes, they were against it, although in the end they admitted that all their
arguments against it were specious and they were simply unwilling to change
their "perfect" class to allow it to be subclassed.  (I claim and am willing
to demonstrate that any overhead is negligible in real performance terms).

Concerning derivation from TNamed, I am also more than a little skeptical
about the notion that adding two strings is going to be a noticeable
performance problem in this age when memory of even low-end computers are
typically measured in 100's of MB.  I think allowing more powerful and
understandable code to be written is far more important than saving a few
bytes here and there, but anyway.

Following that discussion, I had a mail from Fons (I think) where he said
that the destructor would be made virtual (in the Root classes, not CLHEP)
in "the next release", but that he would not adopt my other suggestion of
making the internal variables protected rather than private.

If George Heintzelman's remark that they already have virtual destructors
due to derivation from a class with a virtual destructor, then the question
is moot, of course.  I haven't tested whether this is true for my compiler,
but I guess I will.

In regard to my earlier question about writing TFolder, there were no
immediate replies to my question, so I tested it and seem to be able to
write a TFolder (and a class derived from TFolder) to an (unbranched) Tree
and read it back from the file without any problems.  This is in a
self-contained, statically linked program; since the graphics plotting
utilities don't really work on Windows I haven't tried it in an interactive
environment yet.


Dave
dcasper@uci.edu



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