This section describes the functions for accessing and storing associations in a hash table. In general, any Lisp object can be used as a hash key, unless the comparison method imposes limits. Any Lisp object can also be used as the value.
This function looks up key in table, and returns its associated value—or default, if key has no association in table.
This function enters an association for key in table, with value value. If key already has an association in table, value replaces the old associated value. This function always returns value.
This function removes the association for key from table, if
there is one. If key has no association, remhash
does
nothing.
Common Lisp note: In Common Lisp, remhash
returns
non-nil
if it actually removed an association and nil
otherwise. In Emacs Lisp, remhash
always returns nil
.
This function removes all the associations from hash table table,
so that it becomes empty. This is also called clearing the hash
table. clrhash
returns the empty table.
This function calls function once for each of the associations in
table. The function function should accept two
arguments—a key listed in table, and its associated
value. maphash
returns nil
.