Sends Mesg to Obj. A send message. The class of Obj must have a method defined for this message.
A clause with
<-/2 as the principal functor of its head is a
method definition clause. Such clauses only occur within the scope of
a class definition. They are expanded at compile time.
For reasons of efficiency, an
exception will only be raised if the code that sends the message is
compiled with debugging enabled (see
debug_message), or if the
message is not determined at compile-time. In other circumstances,
the message will simply fail.
Calls to the
<-/2 predicate will be compiled into
more efficient code if the
obj_decl module is loaded at compile time.