A recent comment to my regexp datatype contribution reminded me of an irritating shortcoming in eZ publish. It’s not possible for datatypes to send error messages back into the class edit. It’s only implemented on the object level for some bizarre and obscure reason.
I plan to incorporate class-level error messages in the next release of the datatype (expect the release soonish) but it’s a real shame that this shortcoming has survived 8 releases so far.
But for now, back to C# 😉