On Thu, Mar 5, 2015 at 6:48 AM, Constantine Yannakopoulos <
alfasud...@gmail.com> wrote:
> On Thu, Mar 5, 2015 at 2:11 AM, silvioprog <silviop...@gmail.com> wrote:
>
>> What do you think about a TDataSetEnumerator class in the DB unit?
>> Something like this:
>>
>> === begin code ===
>>
>>
> function TDataSetEnumerator.MoveNext: Boolean;
>> begin
>> Inc(FPosition);
>> if FPosition = FDataSet.RecordCount then
>> Exit(False);
>> FDataSet.MoveBy(FPosition);
>> Result := True;
>> end;
>>
>
> I'm not sure for FPC but in Delphi there are datasets that do not fully
> implement the properties .RecNo and .RecordCount, server cursor datasets
> for example always return -1 if memory serves. IMHO the .MoveNext method
> should be written in such a way as to not use .RecordCount but only .Eof
> which is the only property that is guaranteed to always work correctly in
> all datasets.
>
Thanks for the information.
So we can change it to (FCL have no a .MoveNext, so I used the .Next
method):
=== begin code ===
TDataSetEnumerator = class
private
FDataSet: TDataSet;
FFirstDone: Boolean;
function GetCurrent: TDataSet;
public
constructor Create(ADataSet: TDataSet);
function MoveNext: Boolean;
property Current: TDataSet read GetCurrent;
end;
...
constructor TDataSetEnumerator.Create(ADataSet: TDataSet);
begin
inherited Create;
FDataSet := ADataSet;
FDataSet.First;
end;
function TDataSetEnumerator.GetCurrent: TDataSet;
begin
Result := FDataSet;
end;
function TDataSetEnumerator.MoveNext: Boolean;
begin
if FFirstDone then
FDataSet.Next
else
FFirstDone := True;
Result := not FDataSet.EOF;
end;
=== end code ===
Thank you!
--
Silvio Clécio
My public projects - github.com/silvioprog
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