Is Delphi "with" keyword a bad practice?

I been reading bad things about the with keyword in delphi but, in my opinion, if you don't over use it. It can make your code look simple.

I often put all my TClientDataSets and TFields in TDataModules. So in my forms I had code like this

procedure TMyForm.AddButtonClick(Sender: TObject);
begin  
  with LongNameDataModule do
  begin
     LongNameTable1.Insert;
     LongNameTable1_Field1.Value := "some value";
     LongNameTable1_Field2.Value := LongNameTable2_LongNameField1.Value;
     LongNameTable1_Field3.Value := LongNameTable3_LongNameField1.Value;
     LongNameTable1_Field4.Value := LongNameTable4_LongNameField1.Value;
     LongNameTable1.Post;
  end
end;

without the with keyword I have to write the code like this

    procedure TMyForm.AddButtonClick(Sender: TObject);
    begin            
      LongNameDataModule.LongNameTable1.Insert;
      LongNameDataModule.LongNameTable1_LongNameField1.Value := "some value";

      LongNameDataModule.LongNameTable1_LongNameField2.Value :=
               LongNameDataModule.LongNameTable2_LongNameField1.Value;

      LongNameDataModule.LongNameTable1_LongNameField3.Value :=
               LongNameDataModule.LongNameTable3_LongNameField1.Value;

      LongNameDataModule.LongNameTable1_LongNameField4.Value :=
               LongNameDataModule.LongNameTable4_LongNameField1.Value;

      LongNameDataModule.LongNameTable1.Post;
    end;

I think is easier to read using the with keyword.

Should I avoid using the with keyword?

delphi with-statement

Edit Report

The main problem with "with" is that you don't know where its scope ends, and you could have multiple overlapping with statements.

I don't think you should avoid using it, as long as your code is readable.

One of the proposals to make it more readable (and less confusing in longer code) was if codegear added the option to allow for aliases in with, and probably allowing multiple withs in one:

procedure TMyForm.AddButtonClick(Sender: TObject);
begin  
  with LongNameDataModule as dm, dm.LongNameTable1 as t1, dm.LongNameTable2 as t2 do
  begin
    t1.Insert;
    t1.FieldByName('Field1').AsString := 'some value';
    t1.FieldByName('Field2').AsString := t2.FieldByName('Field2').AsString;
    t1.Post;
    dm.Connection.Commit;
  end
end;

answered 2009-02-05T04:07:29.610

Is Delphi "with" keyword a bad practice?

1 Answer

Your Answer