Question
Is it possible to restrict a type parameter to be a reference type? I see you can use T(!new) but I’m looking for the opposite.
Answer
No. The only restrictions available (as of version 3.7.3) are
T(==)- type supports equalityT(0)- type is auto-initializableT(00)- type is non-emptyT(!new)- type may not be a reference type or contain a reference type
See the appropriate section of the reference manual for more information.