On 06.11.2015 22:45, Mark Morgan Lloyd wrote:
Luca Olivetti wrote:
with a=somerecord, b=someotherrecord do
begin
a.x:=b.x;
end;
Just because something is 20+ years old doesn't necessarily make it
bad. That syntax looks OK to me (i.e. make a and b look like consts)
but I also find myself wondering what the type rules are, i.e.
with pod: TTabSheet= Pages.Objects[deleteAt] do
vs
with pod= TTabSheet(Pages.Objects[deleteAt]) do
Do not forget that you can overload operators! In particular you can
overload the comparison operator to return a record, so your
"with a=somerecord do" can already be a valid pascal code now:
*type**
** TMyRec = record**
** I: Integer;**
** end;**
**
** TMyResult = record**
** Res: Integer;**
** end;**
**
**operator = (z1: TMyRec; z2 : TMyRec) b : TMyResult;**
**begin**
** Result.Res := z1.I+z2.I;**
**end;**
**
**var**
** m1, m2: TMyRec;**
**begin**
** m1.I := 10;**
** m2.I := 1;**
** with m1=m2 do**
** writeln(Res);**
** readln;**
**end.*
The assignment operator would be better, since it doesn't return a value
(in pascal, of course) and thus cannot be used in a with statement now:
*with a:=somerecord, b:=someotherrecord do**
**begin**
** a.x:=b.x;**
**end; **
*
IMO there is no need to set a type of a/b on the left side of the with
assignment - the left side should always gain the type from the the
right side. In this case you can decide whether the "AS" or the direct
re-type should be used:
*with pod := Pages.Objects[deleteAt] as TTabSheet do **
**with pod := TTabSheet(Pages.Objects[deleteAt]) do **
*
-> both are valid and the syntax is already in pascal - why not to use it.
Ondrej
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