To follow up on the discussion started in 04fdedc#r138624434, @brownbaerchen @lisawim (and also centralize all that have been done on this topic, don't hesitate to complement the description ...)

Workspace dev branch : https://github.com/brownbaerchen/pySDC/tree/multicompmeshv3

Current testing : https://github.com/brownbaerchen/pySDC/blob/multicompmeshv3/pySDC/tests/test_datatypes/test_multicomponent_mesh.py

Requirements :

• easy-to-use and generic implementation
• most operations (including numpy operators) conserve the type
• allow to access and modify the different components using a view on the same global array containing all components
• use for other current data classes : imex, multi-implicit, (particules ?)

Some preliminary works (some time ago ...) :

• base generic class : https://github.com/Parallel-in-Time/pySDC/blob/master/pySDC/playgrounds/datatypes/base.py
• application for mesh and others : https://github.com/Parallel-in-Time/pySDC/blob/master/pySDC/playgrounds/datatypes/implementations.py
• some tests for consistency : https://github.com/Parallel-in-Time/pySDC/blob/master/pySDC/playgrounds/datatypes/check_consistency.py
• some tests for performance : https://github.com/Parallel-in-Time/pySDC/blob/master/pySDC/playgrounds/datatypes/check_performance.py

$\Rightarrow$ main idea is to have a base multi-component class that can be used later for fenics, petsc, etc ...