Invocation.setter constructor

Invocation.setter(Symbol memberName, Object argument)

Creates an invocation corresponding to a setter invocation.

This constructor accepts any Symbol as memberName, but remember that actual setter names end in =, so the invocation corresponding to object.member = value is

Invocation.setter(const Symbol("member="), value)

Implementation 

factory Invocation.setter(Symbol memberName, Object argument) =
    _Invocation.setter;