On 08.01.2017 10:35, Ryan Joseph wrote: > >> On Jan 8, 2017, at 2:37 AM, Andrew Hall <andrew.h...@shaw.ca> wrote: >> >> If you cast your “something” to a typed pointer, the compiler will do the >> work for you in the usual way: >> >> PDouble(something)^ := myDouble; >> PAnsiString(something)^ := myAnsiString; >> myRecordStructure := PMyRecordStructure(something)^; > > I’m not getting any of this to work. > > Here is the pattern I was attempting. It’s a “release existing, retain and > assign new” function which handles nil inputs safely. I thought I could use > untyped params so I don’t need to typecast “io” to TObject when I call > RetainObject every time. > > procedure RetainObject (var io; newObject: TObject); > var > obj: TObject absolute io; > begin > if obj <> nil then > obj.Release; > if newObject <> nil then > begin > obj := newObject; > obj.Retain; > end > else > obj := nil; > > TObjectPtr(io)^ := obj; // crashes here > end;
1. Why are you trying to assign something to io when you already did that with "obj := ..."? 2. TObject is an implicit pointer, so "TObject(io) := ..." would be correct (see the implementation of FreeAndNil() in $fpc/rtl/objpas/sysutils/sysutils.inc) [otherwise your usage of "obj" would already crash] Regards, Sven _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
