🚀 go-pugleaf

re: How can I get rid of the unnecessary instances after I've used them?

By not "pointing" at them.   Let the GC do it's thing.


Seriously.  This question is asked every 6 months or so on this
mailing list, and evokes the remembrance of "destructors" in C++.
But the concept of "getting rid" of something in Lisp has been
around for over 30 years, and it's the same issue for "instances"
as it is for CONS cells and most other objects.

Howver, note that certain kinds of objects are "registered" in global
places, and will not be reclaimed simply because the user has dropped
all pointers to them from his code.  The Common-Lisp PACKAGE system has 
a registry that maps strings into PACKAGE's, as well as the obvious set 
of mappings form strings into SYMBOL's; and CLOS obviously is mapping 
class-names into CLASS objects.  There may be other registrations like
this depending on the implementation.

For example, in order to "get rid of" a symbol, you may have to call
UNINTERN numerous times; and to get rid of a package, you may have to
call DELETE-PACKAGE (see CLtL2).  And a few CLOS implementation support 
a partial function for DELETE-CLASS, although this function isn't in
the ANSI CL proposal (I say "partial", because depending on the class 
inheritance topology, this isn't always a well defined operation.)




-- JonL --