The default method for vec_ptype_full()
uses the first element of the
class vector. Override this method if your class has parameters that should
be prominently displayed.
The default method for vec_ptype_abbr()
abbreviate()
s vec_ptype_full()
to 8 characters. You should almost always override, aiming for 4-6
characters where possible.
These arguments are handled by the generic and not passed to methods:
prefix_named
suffix_shape