Exposing TGraph by name to interpreter

Can someone explain what to me seems like an inconsistency in the behavior of root?

{ TH1F* h = new TH1F("hhhh", "hhhh", 10, 0, 0); TH1F* j = new TH1F("jjjj", "jjjj", 10, 0, 0); j->SetName("qqqq"); Double_t a[10]; Double_t b[10]; TGraph*g = new TGraph(10, a, b); g->SetName("gggg"); }

Now I run invoke root with this script. I understand and/or accept the behavior of the histograms and their availability in the interpreter by either the variable reference or their named value. I notice that when I rename “jjjj” to “qqqq” that gROOT can find “qqqq”. Why is it that gROOT can’t find “g” or “gggg” but “g” is available in this session?

I suppose that my somewhat aimless meanderings are behind this one question: How do I get TGraphs to behave in the interpreter like histograms? (I want to make many TGraphs and SetName to varying strings to access them on the command line. If I write them to a root file I can get them by name like “gggg” but I don’t want to have to do that intermediate writing).

[mwoods ~] $ root roottest.cc root [0] Processing roottest.cc... root [1] h (class TH1F*)0x7f9ddaa6e380 root [2] hhhh (class TH1F*)0x7f9ddaa6e380 root [3] j (class TH1F*)0x7f9ddaa6ea50 root [4] jjjj Error: Symbol jjjj is not defined in current scope (tmpfile):1: *** Interpreter error recovered *** root [5] qqqq (class TH1F*)0x7f9ddaa6ea50 root [6] g (class TGraph*)0x7f9ddaa79480 root [7] gggg Error: Symbol gggg is not defined in current scope (tmpfile):1: *** Interpreter error recovered *** root [8] .ls OBJ: TH1F hhhh hhhh : 0 at: 0x7f9ddaa6e380 OBJ: TH1F qqqq jjjj : 0 at: 0x7f9ddaa6ea50 root [9] gROOT->Get("hhhh") (class TObject*)0x7fb4d1a6e4d0 root [10] gROOT->Get("h") (class TObject*)0x0 root [11] gROOT->Get("qqqq") (class TObject*)0x7fb4d1a6eba0 root [12] gROOT->Get("gggg") (class TObject*)0x0 root [13]

Well, I would try to add:
but then, for example, when you try to “gggg->Draw(…);” it, you will get (just once):
Warning in TROOT::Append: Replacing existing TH1: gggg (Potential memory leak).
See also: [url]Drawing TGraph versus TH1F
Well, you might try to be clever and do:
delete g->GetHistogram(); g->SetHistogram(0);
But this won’t help … see also [url]Graph initialized in loop: annoying “memory leak” message
Note that, if you draw it right after you create it (and set its name), you will automatically get it elsewhere afterwards (just like you were going through an “intermediate” file).