[gclist] Finalization and death notices

Thomas F. Burdick tfb@OCF.Berkeley.EDU
Mon, 8 Oct 2001 23:31:47 -0700

Jerrold Leichter writes:
 > | This seems to come back to the same old debate about GC for
 > | C++ -- to finalize or not to finalize, and if so how?  We
 > | go round and round looking for the "right" way, whereas java
 > | just went ahead and did it wrong, and users soon learned
 > | that finalizers were nearly useless.  And lacking destructors
 > | they learned to manage resources with finally clauses.
 > Which actually brings us back to a fundamental point that gets lost in too
 > much of the discussion of C++, destructors, and finalizers:  The fundamental
 > difference between lexically and dynamically determined lifetimes.
 > When C++ programmers complain that finalizers don't run immediately, what they
 > usually have in mind is the "initialization is resource acquisition" (hence,
 > the "destruction is resource deacquisition") idiom.  However, this idiom
 > really only makes sense for stack-allocated objects.  Like a finally clause,
 > IRA/DRD deals with the need to clean up resources that live only in a
 > lexically defined scope - but a scope with multiple exits, often because of
 > the possibility of exceptions escaping the scope.  No one has proposed using
 > gc for stack-allocated objects - and if a compiler can determine the lexical
 > lifetime of a heap-allocated object, it can certainly arrange to have it
 > deleted directly, without gc involvement.

Actually, you're talking about dynamic extent versus indefinate
extent, not lexical vs dynamic scope.