Availability:built-in
b_getval(+Name,
-Value)Get the value associated with the global variable Name and
unify it with Value. Note that this unification may further
instantiate the value of the global variable. If this is undesirable the
normal precautions (double negation or copy_term/2)
must be taken. The
b_getval/2
predicate generates errors if Name is not an atom or the
requested variable does not exist.