New/old style trigger API

The docs seem a little sketchy but the source implies that there is
a difference between new and old style triggers. I can't seem to find
this difference. I tried following the only current example I could
find but I get a core dump. Here is the backtrace.

#0 0x0 in ?? ()
#1 0x8136052 in fmgr_oldstyle (fcinfo=0xbfbfd134) at fmgr.c:433
#2 0x80b6b2d in ExecCallTriggerFunc (trigger=0x82ce030, trigdata=0xbfbfd1c8,
per_tuple_context=0x827acf0) at trigger.c:865
#3 0x80b6e15 in ExecBRUpdateTriggers (estate=0x82fbf50, tupleid=0xbfbfd264,
newtuple=0x83094a8) at trigger.c:1008
#4 0x80bcf3a in ExecReplace (slot=0x8308018, tupleid=0xbfbfd264,
estate=0x82fbf50) at execMain.c:1416
#5 0x80bcc82 in ExecutePlan (estate=0x82fbf50, plan=0x82fbec8,
operation=CMD_UPDATE, numberTuples=0, direction=ForwardScanDirection,
destfunc=0x83092f0) at execMain.c:1127
#6 0x80bc27b in ExecutorRun (queryDesc=0x8307cc0, estate=0x82fbf50,
feature=3, count=0) at execMain.c:233
#7 0x80ff29b in ProcessQuery (parsetree=0x82f6e20, plan=0x82fbec8,
dest=Remote) at pquery.c:277
#8 0x80fddd3 in pg_exec_query_string (
query_string=0x82f6030 "UPDATE bgroup SET actypid = 1,ddate = NULL,edate = '2001-07-23',mail = '',ftp = '',dns = 'f',bname = 'jpsantos',bgdesc = '',isp = 'VEX',pdate = '2001-04-23',pmon = 5,bgroup_active = 't',sdate = '1999-"...,
dest=Remote, parse_context=0x827a720) at postgres.c:808
#9 0x80fedd1 in PostgresMain (argc=4, argv=0xbfbfd4c8, real_argc=9,
real_argv=0xbfbfdc54, username=0x826325d "darcy") at postgres.c:1905
#10 0x80ea2ad in DoBackend (port=0x8263000) at postmaster.c:2114
#11 0x80e9eb2 in BackendStartup (port=0x8263000) at postmaster.c:1897
#12 0x80e91aa in ServerLoop () at postmaster.c:995
#13 0x80e8b7c in PostmasterMain (argc=9, argv=0xbfbfdc54) at postmaster.c:685
#14 0x80caff4 in main (argc=9, argv=0xbfbfdc54) at main.c:175
#15 0x806bc81 in ___start ()

It gets to fmgr_oldstyle() and then dies from a jump to a null pointer.
Can someone please tell me how to make my function a newstyle one. I
will update the docs once I have it working.

--
D'Arcy J.M. Cain <darcy(at){druid|vex}.net> | Democracy is three wolves
http://www.druid.net/darcy/ | and a sheep voting on
+1 416 425 1212 (DoD#0082) (eNTP) | what's for dinner.