[fpc-pascal] if-then-else expression

[Serguei TARASSOV]

On 03/02/2016 12:00, fpc-pascal-request at lists.freepascal.org wrote:
> Date: Tue, 2 Feb 2016 19:43:02 -0700 (MST)
> From: silvioprog<silvioprog at gmail.com>
>
>> >The problem with Iff() is:1) it either retains normal function behavior
>> >and thus has to evaluate both expressions (i.e. suboptimal performance and
>> >allowing side effects);
> Well:
> program Project1;  function test1: integer;  begin    WriteLn('A');
> Result := 10;  end;  function test2: integer;  begin    WriteLn('B');
> Result := 20;  end;  function CommonFunc(A: Boolean; B, C: integer):
> integer;  begin    if A then      Result := B    else      Result := C;
> end;var  X: LongInt;begin  X := IfThen(True, test1, test2);  WriteLn(X);
> WriteLn('----');  X := CommonFunc(True, test1, test2);  WriteLn(X);
> ReadLn;end.
> Result:
> A10----BA10
Holy sh*t, ça continue ! :)
Even if evaluation order will be assured and well documented, it doesn't 
make sense!
Example :

x := iif(Obj = nil, 0, Obj.Value); // Seems OK when right-to-left and 
stop on 'true' evalation
x := iif(Obj <> nil, Obj.Value, 0); // Raise access violation

Regards,
Serguei