[fpc-pascal] Re: Generics - how to rewrite TOjectDictionary

[dmitry boyarintsev]

You can always use functions, to fight typecasting.

function GetMyObject(dic: TStrings; const nm: string): TMyObject;
var
  i : integer;
begin
  if not Assigned(dic) then begin Result:=nil; Exit; end;
  i:=dic.indexof(nm); // replace with IndexOfName if necessary
  if (i<0) or (i>=dic.Count) or not (i.Objects[i] is TMyObject) then
Result:=nil
  else Result:=TMyObject(i.Objects[i]); // not using "as" , since "is" has
already been used
end;

Of course, people would use ClassHelpers these days to have nice syntax and
avoid the sanity check.

thanks,
Dmitry


On Mon, Apr 8, 2013 at 1:42 AM, Marius2 <fpclazarus at home.nl> wrote:

> Thanks Dimitri,
>
> Yes, I have used it lots of times and its really the last choice if theres
> something available like the objectdictionary. In this case the dict is
> also
> the owner of the objects, it saves me the continious ugly typecasting,
> takes
> care of the extra administration with freeing objects and all the
> additional
> troubles you get over time with this solution (its not as bad as i'm
> telling
> now). In other words tstrings.objects are working fine, but i find it a bad
> strategy if you have to use it in flatout in the whole application.
>
> I'm curious how to rewrite/solve dictionaries, indexed list and even sorted
> strings.objects to a neat solution while (if possible) working with both
> delphi and fpc/laz.
>
> Greetings,
> Marius
>
>
>
>
>
> --
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