Help with 'Continue' pls.

[Ian Branch 121]

Hi Team,

Using D12.

It may be my missunderstanding but..

I have the following code:

    Suppliers.First;
    //
    while not Suppliers.eof do
    begin
      //
      sSelected := Suppliers.FieldByName('SupplierCode').AsString;
      sDescription := Suppliers.FieldByName('SupplName').AsString;
      //
      Parts.Close;
      Parts.SQL.Clear;
      Parts.SQL.Text := 'Select * from Parts where SupplierCode = ' + quotedStr(sSelected) + ' and BusCode = ' + QuotedStr(sBusCode);
      Parts.Prepare;
      Parts.Open;
      //
      if Parts.eof then
      begin
        //        TaskMessageDlg('No parts available!', 'There are no Parts on record for Supplier - ' + sDescription + ' at location ' + sLocation + '.',
        //          mtInformation, [mbOK], 0)
        Label1.Caption := 'There are no Parts on record for Supplier - ' + sDescription + ' at location ' + sLocation + '.';
        //
        Suppliers.Next;
        //
        Continue;
        //
      end
      else
      begin
        //

Omitting the Suppliers.Next for the moment, I allways thought that a Continue would have automatically caused Suppliers to move to the next record by virtue of the 'while not Suppliers.eof do'.

In my case of the code above, it doesn't, I had to insert the Suppliers.Next; line.

Was my understand incorrect or is there some other explanation?

 

Regards & TIA,

Ian

[Stano 140]

https://docwiki.embarcadero.com/RADStudio/Athens/en/Continue

[Ian Branch 121]

Hi Stano,

Tks for the reference.

OK, so it doesn't cause the step.

I need to review a few other pieces of code.  😞

Rightly or wrongly, I have always worked on it stepping.

 

Edited January 11 by Ian Branch

[Stano 140]

I'm avoiding the Continue command. I use it exceptionally. en when I need to skip/skip something. At least that's how I understand it. So I usually have it in some if..then..else... branch.  
In the above example it has no meaning. I suppose this is just a symbolic demonstration.

[Remy Lebeau 1260]

On 1/11/2024 at 10:19 AM, Ian Branch said:

I allways thought that a Continue would have automatically caused Suppliers to move to the next record by virtue of the 'while not Suppliers.eof do'.

Nope.  Eof simply evaluates the current record, it does not move to another record.  Hence the need to call Next() explicitly.

On 1/11/2024 at 10:19 AM, Ian Branch said:

Was my understand incorrect

Yes.

Edited January 12 by Remy Lebeau

[Ian Branch 121]

Thanks Guys,

It's surprising I have operated under this missunderstanding for so long.... 😞

All good now.

Again, thank you.

 

Regards,

Ian

[Uwe Raabe 1890]

57 minutes ago, Remy Lebeau said:

If you want the loop to iterate through the records automatically, use a for..in loop instead, see Iteration Over Datasets Using For Statements, for example:

Did you actually try that? 

 

Even in Delphi 12 this report is still valid: https://quality.embarcadero.com/browse/RSP-39614 

[Remy Lebeau 1260]

36 minutes ago, Uwe Raabe said:

Did you actually try that? 

No. I just knew the feature supposedly exists.

Quote

Even in Delphi 12 this report is still valid: https://quality.embarcadero.com/browse/RSP-39614 

Ouch! And not even opened for review yet....

Edited January 11 by Remy Lebeau

[Uwe Raabe 1890]

It basically one of the rare cases when documentation was updated, but the underlying feature was dropped just before the release for several reasons. So it boils down to just fix the docs.

[Anders Melander 1639]

2 hours ago, Uwe Raabe said:

the underlying feature was dropped

And thank Flying Spaghetti Monster for that. What a horrible design.

[Uwe Raabe 1890]

I know, most likely I'm biased, but I'm not aware of any other working dataset enumerator than this one: https://github.com/UweRaabe/DataSetEnumerator. First described a couple of years ago on my blog: Dataset Enumerator Reloaded and now part of CmonLib.