If you call sqlite3_create_function_v2() with a function name that is the name of a built-in function, then the built-in function goes away and is replaced by your application-defined function. The original built-in function is no longer accessible. *Any* built-in function can be overloaded in this way.
On Wed, Sep 11, 2013 at 4:35 PM, Stephan Beal <sgb...@googlemail.com> wrote: > Hi, all, > > i'm looking for a clarification on what is certainly a bit of pedantry on > my part: > > http://www.sqlite.org/c3ref/create_function.html > > specifies that we can overload built-in funcs with UDFs: > > "Built-in functions may be overloaded by new application-defined > functions." > > Does "overload" imply "override" if the name/arg count/encoding/state > match, or is it an error to override a function? The docs don't seem to > explicitly mention the (admittedly unusual) exact-match case, but the > paragraph above that one seem to be intended that a name/arg-count overload > is an error: > > "It is permitted to register multiple implementations of the same functions > with the same name but with either differing numbers of arguments or > differing preferred text encodings." > > > i've been on this list long enough to know that someone out there is going > to ask, "why would you do that?" In brief: in porting the Fossil SCM to a > library API i need to use a different approach to how it overrides > localtime() with its own variant (it uses a C macro to replace localtime() > with fossil_localtime(), which uses app-global state, whereas i have a > library API and thus local state), and currently overriding it, as opposed > to overloading it, is what i'm aiming to do (when the time comes to port > those bits, which isn't tonight). But... i won't if you guys can tell me in > advance that it will fail. > > Happy Hacking! > > -- > ----- stephan beal > http://wanderinghorse.net/home/stephan/ > http://gplus.to/sgbeal > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
