On Thu, 5 Mar 2015, silvioprog wrote:
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;
You should check here for unidirectional datasets. They do not support .first.
For unidirectional datasets you can only go from the current point forward.
Michael.
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