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Erica Snider, 06/14/2016 03:50 PM

Developing With LArSoft

Quick links for Developing with LArSoft


To design LArSoft code, it's important to understand the core LArSoft suite and all the components used by it. Reference the items below when designing new software.

LArSoft architecture and design principles

Latest architecture document as PDF download

Design principles on

LArSoft repositories

The art framework and the LArSoft suite

External packages

These are package written and maintained by the general physics and computing communities.

Package Namespace Short description Location of headers
C++ std:: Extensions to base C++ that are part of the standard language
ROOT See below Data-analysis tools $ROOT_INC
CLHEP CLHEP:: Class Library for High-Energy Physics $CLHEP_INC/CLHEP
Geant4 See below Detector simulations $G4INCLUDE
GENIE genie:: Neutrino Monte-Carlo Generator $GENIE_INC/GENIE
boost boost:: General programming tools for C++ $BOOST_INC/boost
Message Facility wiki documentation mf:: Service for console messages $MESSAGEFACILITY_INC/
nutools and LArSoft simb:: ... Neutrino platform tools $NUTOOLS_INC

ROOT and Geant4 do not use namespaces. In general, ROOT classes begin with "T" (e.g., TTree, TH1) while Geant4 classes begin with "G4" (e.g., G4Track, G4Step). Exception: Some of the newer ROOT sub-packages have namespaces (such as ROOT::Math::, ROOT::Fit::, ROOT::Minuit2::, Reflex::, TMVA::).

Some of these packages duplicate functionality; e.g., 4-vectors are implemented in both ROOT and CLHEP. Given a choice, use a package that's higher in the above tables over one that's lower; e.g., choose ROOT classes over their CLHEP equivalents.

Writing code

Whether you are writing new code or modifying existing code, please follow the guidelines listed below. There are also development tools and techniques available that can make coding easier.


Tools and techniques

git and git flow

  • git guidelines
  • git flow quick start
  • Git Tips and Tricks (Note that "git help" works, but "man git" and "git help <command>" does not on any of the gpvm machines. Nor do any of the "git <command> -h" commands.) For the purposes of LArSoft development, please please ignore the workflow advice as anything other than an example of how to use various git commands to do specific tasks.



Debugging LArSoft


How to use the repositories and the build system

Understanding CMakeLists.txt and product_deps files mrb and ups:


High-level description of testing is available at

LArSoft Continuous Integration (CI) system

Getting software into a LArSoft release

After designing, coding, building and testing a piece of software, submit it to the LArSoft development branch so it is included in a new release.