Add a header file including all the collections

[jmcarcell]

BEGINRELEASENOTES

• Add a header file including all the collections in the datamodel. This header will be generated and installed into <datamodel>/<datamodel>.h.

ENDRELEASENOTES

The usage would be

#include "edm4hep/edm4hep.h"

and all the collections will be included.

I find from time to time I need to do something with all the collections and after having a look at other options (hardcoding the includes means they always have to be changed; having some CMake magic in EDM4hep to generate this file is an option but it also can be done at the podio level) I think this is the cleanest one and other people can maybe also use it. In practice, if an algorithm does something with the collections and a new one is added, even if the include doesn't change because it comes from this file other code that does something with collections will have to be changed.

[jmcarcell]

Looks reasonable to me. I am not sure if AllCollections.h is the best name, but I don't have a better one either. Maybe something that conveys better that this is the complete datamodel?

You also need to add the new template here to trigger re-generation in case the template changes: master/python/templates/CMakeLists.txt

I changed it to, for example for EDM4hep, edm4hep/Alledm4hepCollections.h

[hegner]

Why don't we just call it edm4hep/edm4hep.h ? Because it is just edm4hep we are including with that. Or datamodel/datamodel.h ?

[m-fila]

I think I prefer edm4hep/AllCollections.h over edm4hep/Alledm4hepCollections.h but just edm4hep/Collections.h reads even better for me Name of this header technically becomes reserved for componenents/datatatypes/interfaces (for instance 'DatamodelDefinition' is already reserved as using it as a name for anything would collide with DatamodelDefinition.h). It's super formal and pedantic but a list of reserved keywords could be documented and potentially validated

Maybe something that conveys better that this is the complete datamodel?

edm4hep/Datamodel.hor edm4hep/edm4hep.h? Wouldn't the components not used in any datatype be missing though?

[hegner]

edm4hep/Datamodel.hor edm4hep/edm4hep.h? Wouldn't the components not used in any datatype be missing though?

the missing components won't be needed in any case. Maybe for downstream code that would then include explicitly anyhow.

[tmadlener]

As decided during the EDM4hep meeting on Jun 4 the name of the header should be datamodel/datamodel.h.

[tmadlener]

I changed the name of the generated header and also changed the generator logic to ensure that it is installed, as I don't see a reason not to install it.

[jmcarcell]

Looks good