podio

Prerequisites

If you are on lxplus, all the necessary software is preinstalled.

On Mac OS or Ubuntu, you need to install the following software.

ROOT 6.06

Install ROOT 6.06 and set up your ROOT environment:

source <root_path>/bin/thisroot.sh

Python 2.7

Check the python version by doing:

python --version

Check that the yaml python module is available

python
>>> import yaml

If the import goes fine (no message), you're all set. If not, you need to install yaml. For that, you need to:

1- install the C++ yaml library, which is used by the python module. On Mac OS, The easiest way to do that is to use homebrew (install homebrew if you don't have it yet):

brew install libyaml

2- install the python yaml module (first install pip if you don't have it yet)

pip install yaml

Check that you can now import the yaml module in python.

Preparing the environment

Before building and installing this package, and everytime you need to use it, do:

source ./init.sh

Compiling

Set up separate build and install areas, and trigger the build:

mkdir build
mkdir install
cd build
cmake -DCMAKE_INSTALL_PREFIX=../install ..
make -j 4 install

To see a list of options, do this in the build-directory:

cmake -LH ..

Running

The examples are for creating a file "example.root",

../install/examples/write

reading it again in C++,

../install/examples/read

and reading it again in python,

python ../examples/read.py

Modifying the data model

Podio features an example event data model, fully described in the yaml file examples/datalayout.yaml. The C++ in examples/datamodel/ has been fully generated by a code generation script, python/podio_class_generator.py.

To run the code generation script, do

mkdir ../Tmp
mkdir ../Tmp/data
mkdir ../Tmp/src
python ../python/podio_class_generator.py ../examples/datalayout.yaml ../Tmp data

Running tests

After compilation you can run rudimentary tests with

make test

Unit tests (for developers)

In order to run the unit tests you have to enable them at configuration time with the flag tests. Note that GTest is needed. On lxplus the necessary environment is set up with the init.sh. On MacOS, you'll have to point cmake to your installation if it is local, see the option in braces below assuming you installed it in <g_test_path>.

To configure with unit tests enabled, do:

cmake -DCMAKE_INSTALL_PREFIX=../install -Dpodio_tests=1 (-DCMAKE_PREFIX_PATH=<g_test_path>/install) ..
make test