On Sat, Mar 7, 2015 at 4:27 AM, LacaK <la...@zoznam.sk> wrote: > What if TDataSetEnumerator.Current will return TFields instead of TDataSet > which enumerates? > > Example: > procedure IterateDataSet; > var DataSet, DS: TDataSet; > Flds: TFields; > F: TField; > begin > for Flds in DataSet do > for F in Flds do // DataSet can be still accessed by Flds.DataSet > writeln(F.AsString,'|'); > end; > > I know that it is more or less same ... it depends what will be most > common usage scenario. > In one case it will be better have DataSet in another Fields. > When iterating DataSet IMO only Fields, Recno, Bookmark are usable > properties which changes on each itteration and can be practically used > inside loop. > But I think, that most common scenario will be use only Fields inside loop. > In both cases user must define "control variable" either of TDataSet type > or TFields type. > > (*** Example implementation ***) > type > TDataSetEnumerator = class > private > FDataSet: TDataSet; > FBOF: Boolean; > function GetCurrent: TFields; > public > &nb sp; constructor Create(ADataSet: TDataSet); > function MoveNext: Boolean; > property Current: TFields read GetCurrent; > end; > > operator Enumerator(ADataSet: TDataSet): TDataSetEnumerator; > begin > Result := TDataSetEnumerator.Create(ADataSet); > end; > > constructor TDataSetEnumerator.Create(ADataSet: TDataSet); > begin > inherited Create; > FDataSet := ADataSet; > FBOF := True; > FDataSet.First; > end; > > function TDataSetEnumerator.GetCurrent: TFields; > begin > Result := FDataSet.Fields; > end; > > function TDataSetEnumerator.MoveNext: Boolean; > begin > if FBOF then > FBOF := False > else > FDataSet.Next; > Result := not FDataSet.EOF; > end; > > (* *** *) > > -Laco. >
Very nice. I open a new issue about that ( http://bugs.freepascal.org/view.php?id=27644). =) I have a question. Can I use two or more enum operators in a same unit? -- Silvio Clécio My public projects - github.com/silvioprog
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