[fpc-devel] Array assignment operator

[Gennady Agranov]

On 11/4/2018 5:24 PM, Sven Barth via fpc-devel wrote:
> Am So., 4. Nov. 2018, 20:36 hat Gennady Agranov 
> <gennadyagranov at gmail.com <mailto:gennadyagranov at gmail.com>> geschrieben:
>
>     On 11/4/2018 11:24 AM, Sven Barth via fpc-devel wrote:
>>     Am So., 4. Nov. 2018, 12:23 hat Schindler Karl-Michael
>>     <karl-michael.schindler at web.de
>>     <mailto:karl-michael.schindler at web.de>> geschrieben:
>>
>>
>>
>>         > Am 04.11.2018 um 12:00 schrieb Ben Grasset
>>         <operator97 at gmail.com <mailto:operator97 at gmail.com>>:
>>         >
>>         > From: Ben Grasset <operator97 at gmail.com
>>         <mailto:operator97 at gmail.com>>
>>         > To: FPC-Devel users discussions
>>         <fpc-devel at lists.freepascal.org
>>         <mailto:fpc-devel at lists.freepascal.org>>
>>         > Subject: Re: Array assignment operator
>>         > Message-ID:
>>         <CAL4d7FjPfX-ysT6Z3--fhPR9Pts-N47ksFN6m2pHD7SunzwpJg at mail.gmail.com
>>         <mailto:CAL4d7FjPfX-ysT6Z3--fhPR9Pts-N47ksFN6m2pHD7SunzwpJg at mail.gmail.com>>
>>         > Content-Type: text/plain; charset="utf-8"
>>         >
>>         > On Sat, Nov 3, 2018 at 4:44 PM Gennady Agranov
>>         <gennadyagranov at gmail.com <mailto:gennadyagranov at gmail.com>>
>>         > wrote:
>>         >
>>         >> Hi,
>>         >>
>>         >> Leaving aside the reason why the MiSchi's solution doesn't
>>         work the main
>>         >> question is still not answered :)
>>         >>
>>         >> If you have integer dynamic array "MyArray" is there a way
>>         for the
>>         >> following statement to compile and work correctly:
>>         >>
>>         >> MyArray := 5;
>>         >>
>>         >
>>         > Uh, yes? That's what my example showed.
>>
>>         In your example the length of the array was set to the number
>>         and the elements of the array assigned to their index,
>>         whereas my intention is to keep the length of the array and
>>         fill all elements to the same number.
>>
>>
>>     The operator always creates a new array and does not modify the
>>     existing one.
>>     You'd need to abuse a binary operator (e.g. >< or even <=) for this.
>>
>>     Regards,
>>     Sven
>>
>>
>>
>>     _______________________________________________
>>     fpc-devel maillist  -fpc-devel at lists.freepascal.org
>>     <mailto:fpc-devel at lists.freepascal.org>
>>     http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
>
>     I was thinking that type helper might work - e.g.
>     MyArray.SetValue(5) and with using properties MyArray.Value := 5
>
>     But seems that even simple type helper is not working anymore?
>
>     E.g. I was not able to compile example from
>     http://wiki.freepascal.org/Helper_types :(
>
>     TTypeHelper=  type  helperfor  Integer
>        procedure  SetZero;
>     end;
>
> Did you add {$modeswitch typehelpers}?
>
> If so, what is the error you get?
>
> Regards,
> Sven
>
>
>
> _______________________________________________
> fpc-devel maillist  -  fpc-devel at lists.freepascal.org
> http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel

My error was caused by the fact that I was using delphi mode - when I 
used the mode switch it worked perfectly :)

The original problem is solved - at least the way I see it - in FPC you 
can add method to the array :)

Cool!

Thanks!

{$MODESWITCH TYPEHELPERS}

program arrayset;

type
   abc = array of integer;
   abc_helper = type helper for abc
   procedure SetValue(value: integer);
   procedure Print;
end;

procedure abc_helper.SetValue(value: integer);
var
   i: integer;
begin
   for i := Low(self) to High(self) do
     self[i] := value;
end;

procedure abc_helper.Print;
var
   i: integer;
begin
   for i := Low(self) to High(self) do
     Writeln('[',i,'] = ',self[i]);
end;

var
   a: abc;
begin
   SetLength(a,10);
   a.SetValue(5);
   a.Print;
end.

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