TClassGenerator use?

ROOT
1

Hi,

Here’s what I would like to do, and I’d like to know if TClassGenerator is the way to go.

I open a root file containing a TTree of some custom classes. If I did not load my custom library prior to the opening I know I will get messages like :

Warning in TClass::TClass: no dictionary for class Custom is available

But I know the relationship class name <-> library to load. Could I use a TClassGenerator to trig the loading of the library which contains Custom dictionary ?

If so, well, a code sample of TClassGenerator implementation would be greatly appreciated.

Regards,

2

Hi,

You have at least 3 choice. One it create a TClassGenerator subclass which implements GetClass pretty as

if(strcmp(classname,"knownclassName")==0) gSystem->Load("libWhereKnowClassIs");
Or you can hand code a .rootmap file:

Library.knownclassName: llibWhereKnowClassIs.so
Or, probably best of all you can generate a .rootmap file using rlibmap and you linkdef files.

Cheers,
Philippe.

3

Hi ,

Thanks for the fast (!) answer.

Your solution 1 is what I would have done, but I was wondering about how to implement the other GetClass method : GetClass(const std::type_info& tif, Bool_t load). Is that one needed too ?

BTW, I’m afraid I current cannot use rlibmap, as it seems it’s a “late” addition (I use ROOT 3.05). But sounds good. Is there some doc. for it ; where is the .rootmap read in ?

Thanks,

Regards,

4

rlibmap with linkdef file is new to ROOT 4.00.06.
For the other signature of TClassGenerator I recomment you just implement it as something like:

Error("GetClass with typeid. This should not have been called\n"). Assert(0); return 0;
I.e. since you would get there if your library is not loaded, it should not be possible to pass it a typeid (which would require the library).

Cheers,
Philippe.

5

Thanks,

I guess for the time being (until we upgrade to latest and greatest ROOT), I’ll make a TClassGenerator which reads a rootmap-type file (so when we upgrade, I’ll simply remove my own class generator and let’s root do the job :wink:

Now the question is how can I specify library dependencies in my rootmap file, or may be my question is : what kind of file should I put in the -d option of rlibmap ?

Regards,

6

Hi,

Here is an extract of the system.rootmap:

Library.TProofEvent: libProof.so libTree.so libHist.so libTreePlayer.so Library.TProofProgressDialog: libProofGui.so libProof.so libGui.so

The argument to the option -d is a list of libraries (.so) which your libraries depends on. For example:

bin/rlibmap -r etc/system.rootmap -l lib/libProofGui.so \ -d lib/libProof.so lib/libGui.so -c proof/inc/LinkDefGui.h

Cheers,
Philippe.

7

Thanks.

I’ve done a checkout of root from cvs, and can not find the system.rootmap file in the directory I got, is that normal ?

Also, under ROOT-3.05/07 (Linux RH8), I tried to make my own class generator, and it seems it’s continuously being called with classname=short, double, int etc… Is that a feature or …

Regards,

8

Laurent,

The etc/system.rootmap is created when running
make map

It is also available when important the binary files.

Rene

9

It is the expected behavior. Your implementation should return 0 in this cases.

Cheers,
Philippe.