Question

The title pretty much says it all. I’m using a TClientDataset to store an array of objects, and one of the objects has a member defined as a set of an enumerated type. As I understand it, Delphi sets are bitfields whose size can vary from 1 to 32 bytes depending on how much data they contain, and Delphi doesn’t define a TSetField. What sort of field should I use to load this value into?

Answer 1

You could use a TBytesField or a TBlobField

ClientDataSet1MySet: TBytesField, Size=32

var   MySet: set of Byte;   Bytes: array of Byte; begin   MySet := [1, 2, 4, 8, 16];    // Write   Assert(ClientDataSet1MySet.DataSize >= SizeOf(MySet), 'Data field is too small');    SetLength(Bytes, ClientDataSet1MySet.DataSize);   Move(MySet, Bytes[0], SizeOf(MySet));   ClientDataSet1.Edit;   ClientDataSet1MySet.SetData(@Bytes[0]);   ClientDataSet1.Post;    // Read   SetLength(Bytes, ClientDataSet1MySet.DataSize);   if ClientDataSet1MySet.GetData(@Bytes[0]) then     Move(Bytes[0], MySet, SizeOf(MySet))   else     MySet := []; // NULL end;