ROOT.jl: ROOT bindings for julia

Provides basic access to the CERN ROOT Framework for the Julia language.

Requirements

• Julia v0.5
• The current master branch of CXX.jl (until Cxx.jl v0.1.1 or so is released).
• ROOT-6 (ROOT-5 may work, but is no longer recommended)

Usage

Enable RTTI for Cxx.jl:

export JULIA_CXX_RTTI="1"

Install ROOT.jl:

julia> Pkg.add("ROOT")

ROOT.jl will install a special Julia executable that initializes ROOT before starting Julia. This avoids conflicts between Cling's LLVM instance and Julia's LLVM instance. The ROOT-compatible Julia binary resides at: joinpath(Pkg.dir("ROOT"), "deps", "usr", "bin", "julia").

You can directly use the standard ROOT API via Cxx.jl:

using ROOT, Cxx
cxxinclude("TCanvas.h")
cxxinclude("TH1D.h")

canvas = icxx"new TCanvas();"
hist = icxx"""new TH1D("hist", "Hist", 20, -4, 4);"""
for i in 1:100000
    @cxx hist->Fill(randn())
end
@cxx hist->Draw()
@cxx canvas->SaveAs(pointer("myhist.png"))

Julia API wrappers for specific ROOT functionalities are left to more specialized packages.

Thread-safety

During startup, ROOT.jl will also enable basic thread-safety for ROOT (via TThread::Initialize()).

It is possible to run certain ROOT operations in multi-threaded Julia code (e.g. TTree I/O, provided each thread uses a separate TFile/TTree resp. TChain instance.). However, certain operations (e.g. creating and deleting a TChain) are not thread-safe. Use

lock(gROOTMutex()) do
    # ... non thread-safe code ...
end

for non-thread-safe code blocks within multi-threaded code.