Hi - I'm wondering if there's something special
I need to do in order to be able to use member
functions of a class I store with a TTree in the Draw()
or Scan() functions of the TTree???
I'm using Root 2.23/12.
I have tried storing a class (StGG) with just four members;
a function Gene() wihich returns the float 3.5
a float data member val1
a function Val() which returns val1
a function Add() which adds 1.0 to val1
When I store a bunch of these in a TTree, save it
to a file, and then look at the TTree in the file:
All the values of val1 appear to be correct,
but both Gene() and Val() return garbage.
I store the class in a macro like this:
{
gSystem->Load("...");
TFile a1("gg.root","RECREATE");
StGG* v1 = new StGG();
TTree* m1 = new TTree("myTree","This is my tree");
m1->Branch("br1","StGG",&v1,64000,1);
for (int i=0; i<25; i++) {
v1->Add();
m1->Fill();
}
a1.Write();
a1.Close();
}
I then read it back into memory in another Root
session:
gSystem->Load("...");
TFile a1("gg.root");
TTree* m1 = (TTree*) a1.Get("myTree");
If I type:
m1->Scan("val1");
everything looks like I expect. But if I type
m1->Scan("br1.Val()");
or
m1->Scan("br1.Gene()");
all 25 values come out as zero or garbage.
Scan() doesn't even complain if I enter a
bogus member name - spits back
zeros or garbage also! Draw() at least
requires that I get the member name
correct (e.g., Draw("Val()") returns an
error, while Draw("br1.Val()") draws a hist
with 25 entries at zero).
If I actually allocate an instance of the class,
set the TTree branch address to it, and then
call GetEvent() on the TTree, then the member
functions work correctly on the instance of
the class...
...Just not in the Draw() and Scan() of the TTree.
Anyone know why?
-Gene Van Buren
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