RE: Displaying graphs before main() returns

From: Fine, Valeri <fine_at_bnl.gov>
Date: Wed, 31 May 2006 13:33:28 -0400

Hello Roland

May I comment one thing?

  You wrote:

> This is no longer true in case of a script because it depends on the
> internal state of the CINT.

It seems to me you suppose that making your own so-called "stand-alone" application linked against of ROOT libraries you get rid of the "internal state of CINT"

All your conclusions are based on this hypothesis.

However, it is not correct. Many ROOT classes do use the CINT internally (the best example is the ROOT Signal / Slot communication).

In other words, your proof of the advantages of the stand-alone ROOT-based applications is based on false premises.

Assuming the "internal state of CINT" does exist one may have conclude that making his own "stand alone" application doesn't eliminate it at all.

Therefore, one is advised to use CINT interpreter as the tool to prototype the application and ACLiC to use it in "production" mode.

---

Best regards

                   Valeri

> -----Original Message-----
> From: owner-roottalk_at_pcroot.cern.ch

[mailto:owner-roottalk_at_pcroot.cern.ch] On
> Behalf Of Roland Kuhn
> Sent: Wednesday, May 31, 2006 10:34 AM
> To: Rene Brun
> Cc: Alex Mott; roottalk_at_pcroot.cern.ch
> Subject: Re: [ROOT] Displaying graphs before main() returns
>
> Hi Rene!
>
> On 31 May 2006, at 13:02, Rene Brun wrote:
>
> > Hi Roland,
> >
> > Could you clarify what you mean by
> > "My experience goes exactly in the opposite direction"?
> >
> Your main point is that people don't know what they're doing, give
> useless bug reports and increase general unhappiness. My experience
> is that some user asks me "why does my script crash" and the only
> efficient way to get an answer is to run it in gdb or valgrind, which
> is more complicated for a script than for a compiled program. The
> other problem is that users are lazy and forget to program proper
> cleanup procedures, producing questions like "why does this crash if
> executed twice". To my mind the most important point, however, is
> reproducability. When I do an analysis I have to make sure that I can
> exactly redo every single step and always get the same result. This
> is no longer true in case of a script because it depends on the
> internal state of the CINT. Of course, using proper discipline it is
> also possible to start a fresh ROOT session for every iteration, but
> if everyone had this kind of discipline, then we wouldn't be
> discussing this...
>
> Don't get me wrong, I think that CINT is a pretty cool feature for
> rapid testing and interactive analysis. But I think it is fatal that
> the lead developer so very strongly discourages the use of standalone
> applications.
>
> Finally, writing a main program with standard event loop is really
> _trivial_. The only problem is that there is no error message (or the
> like) which informs the ignorant user that an event loop would be
> beneficial.
>
> > The main program syndrom
> > ========================
> > Of course, nobody prevents you to write your own main program.
> > This is necessary when you implement your own event loop.
> > By event loop, I mean graphics/system event loop.
> >
> > It is much better to execute a script (interpreted or compiled)
> > from the ROOT prompt. This script can load automatically one or
> > more shared libs (plug-ins). Making plug-ins makes your program
> > more modular. It also greatly facilitates our job. In particular,
> > we see many reports where people do not understand what is an
> > event loop. They forget to instantiate a TApplication (or TRint)
> > object. They forget to send the makefile to build the
> > executable, etc.
> >
> > Rene Brun
> >
> > Roland Kuhn wrote:
> >> Hi Rene!
> >>
> >> On 30 May 2006, at 08:37, Rene Brun wrote:
> >>
> >>> If you create your own executable (with a main) and this
> >>> application has graphics,
> >>> you must create a TApplication object. See example in $ROOTSYS/
> >>> test/hworld.cxx
> >>> It is in general a very bad idea to create your own main program.
> >>> You better execute scripts
> >>> from the ROOT prompt.
> >>>
> >> Could you elaborate on this? My experience goes exactly in the
> >> opposite direction.
> >>
> >> Ciao,
> >> Roland
> >>
> >> --
> >> TU Muenchen, Physik-Department E18, James-Franck-Str., 85748
Garching
> >> Telefon 089/289-12575; Telefax 089/289-12570
> >> --
> >> CERN office: 892-1-D23 phone: +41 22 7676540 mobile: +41 76 487
4482
> >> --
> >> UNIX was not designed to stop you from doing stupid things,
> >> because that
> >> would also stop you from doing clever things.
> >> -Doug Gwyn
> >> -----BEGIN GEEK CODE BLOCK-----
> >> Version: 3.12
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> >> M+ !V Y+
> >> PGP++ t+(++) 5 R+ tv-- b+ DI++ e+++>++++ h---- y+++
> >> ------END GEEK CODE BLOCK------
> >>
> >>
> >>
> >>
> >
>
>
> Ciao,
> Roland
>
> --
> TU Muenchen, Physik-Department E18, James-Franck-Str., 85748 Garching
> Telefon 089/289-12575; Telefax 089/289-12570
> --
> CERN office: 892-1-D23 phone: +41 22 7676540 mobile: +41 76 487 4482
> --
> UNIX was not designed to stop you from doing stupid things, because
that
> would also stop you from doing clever things.
> -Doug Gwyn
> -----BEGIN GEEK CODE BLOCK-----
> Version: 3.12
> GS/CS/M/MU d-(++) s:+ a-> C+++ UL++++ P+++ L+++ E(+) W+ !N K- w--- M
> + !V Y+
> PGP++ t+(++) 5 R+ tv-- b+ DI++ e+++>++++ h---- y+++
> ------END GEEK CODE BLOCK------
>
>
>
Received on Wed May 31 2006 - 19:36:28 MEST