ROOT.jl: ROOT bindings for julia

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

Note: This is work in progress, expect bugs and crashes.

Requirements

• Julia v1.3.
• CXX.jl - note that Cxx.jl currently (v0.3.4) doesn't support Julia v1.4 or newer.
• ROOT v6.24.02 or newer (root-config must be on your $PATH).

Usage

Enable RTTI for Cxx.jl:

export JULIA_CXX_RTTI="1"

Install ROOT.jl:

julia> import Pkg;
julia> Pkg.add(Pkg.PackageSpec(url="https://github.com/JuliaHEP/ROOT.jl.git"))

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.

ROOT's graphical user interface

If you want to use ROOT's GUI, run rootgui() to start a Julia timer that runs ROOT GUI loop. To open a TBrowser, for example, run

using ROOT, Cxx

cxxinclude("TBrowser.h")
rootgui()

icxx"new TBrowser();"

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.