On Mar 14, 2010, at 5:21 PM, Marvin Humphrey wrote:
On Sun, Mar 14, 2010 at 02:30:48PM -0500, Peter Karman wrote:
I like this approach. It's more work for KS developers, in terms of
managing
api versions, but that's good work to do, since it requires making
the api
changes very explicit.
I understand that this sounds attractive in theory, but it's not
practical.
Certainly having two versions run side by side won't ever work. We
can't
search-and-replace within compiled XS objects to substitute
"KinoSearch" for
"KinoSearch3". Does Query_Is_A(query, ORQUERY) pass, fail, or
segfault
when "query" was created under KinoSearch3, but ORQUERY is a VTable
owned by
KinoSearch4, aliased to KinoSearch? What should factory methods
spit out, and
how will they know? How will type checking across the Perl/C border
work?
I don’t understand all of what you are saying, but I had in mind
making KinoSearch an alias for KinoSearch4, and not vice versa.
Running multiple versions in the same process I don’t consider a
necessity. Does that change anything?
Changing up behaviors using an api_version key can work within a
single
object, using one of the following strategies:
* Store api_version as a member variable and switch up behavior
based on
its value. That's what HTML::Parser does, I believe.
* Have the constructor dispatch based on api_version and return
objects
blessed into different classes.
* Store an API-specific object within the main object and dispatch
to that.
However, KinoSearch is a highly performance-sensitive library with
hundreds of
classes and lots of interaction between all the various parts.
Furthermore,
it doesn't use hash-based method dispatch, but compile time binding
-- which
is much faster, but also means that invoking an invalid method on an
object
results in a memory error rather than a catchable exception. At
best that's a
segfault, at worst it's a security hole.
Marvin Humphrey
_______________________________________________
kinosearch mailing list
[email protected]
http://rectangular.com/cgi-bin/mailman/listinfo/kinosearch
