Required preCICE version in the preCICE configuration file

[MakisH]

At the moment, when a user tries to use a preCICE v2 configuration file with preCICE v3 (or the reverse), they will just get errors regarding unknown configuration tags.

Since we keep the config compatible in the same preCICE major version, but then also often change it with each major version, I think it would be very helpful to add a <precice-version major="3"> tag, which we could then check and throw a proper error.

We could even extend that to something like <precice-version major="3" minor="5"> to signify that a feature mentioned in this config requires preCICE v3, but at least v3.5.

Retrospectively, we could implement a simple error message that looks for old keywords and complains that This configuration file was probably made for preCICE v1, but you are using preCICE v3.2.0.

Questions:

• Would something like this be helpful?
• Would adding such a tag be feasible?
• Would adding such a heuristic for older versions be feasible?

[BenjaminRodenberg]

There are often rather ranges of compatible versions. To some degree this is covered by semantic versioning already, but one might also need <precice-version major="3" min-minor="5"> or <precice-version min-major="3" max-major="4">. I think this is not so relevant, if we only offer major version here, but if we also allow the user to specify minor versions, this might be over restrictive.

[MakisH]

As I wrote already, I only intended to have a minor as implied min-minor:

We could even extend that to something like <precice-version major="3" minor="5"> to signify that a feature mentioned in this config requires preCICE v3, but at least v3.5.

Do you have any examples of a config that stops being valid during a major version? That would be something we currently don't allow.