To replace a pointer to a pointer with a direct pointer; to replace
an old address with the forwarding address found there. If you telephone
the main number for an institution and ask for a particular person by name,
the operator may tell you that person's extension before connecting you, in
the hopes that you will snap your
pointer and dial direct next time. The underlying metaphor may
be that of a rubber band stretched through a number of intermediate points;
if you remove all the thumbtacks in the middle, it snaps into a straight
line from first to last. See chase pointers.
Often, the behavior of a trampoline is to
perform an error check once and then snap the pointer that invoked it so as
henceforth to bypass the trampoline (and its one-shot error check). In
this context one also speaks of snapping
links. For example, in a LISP implementation, a function
interface trampoline might check to make sure that the caller is passing
the correct number of arguments; if it is, and if the caller and the callee
are both compiled, then snapping the link allows that particular path to
use a direct procedure-call instruction with no further overhead.
