Using provider mode: TPriceList

• Jul 29, 2021

1. Base class structure

2. TPriceList

3. TUserDataSource

4. Creating columns

5. Full code

2. TPriceList

The implementation of the TPriceList class is simple. An empty list is created in the constructor. The Add method adds a new record and initializes it with specified parameters.

Delphi

{ TPriceList }
constructor TPriceList.Create;
begin
  FRecords := TList.Create;
end;
destructor TPriceList.Destroy;
begin
  Clear;
  FRecords.Free;
  inherited Destroy;
end;
procedure TPriceList.Add(ADescription: string; AOnHand: Integer; APrice: Currency);
var
  P: PListEntry;
begin
  New(P);
  FRecords.Add(P);
  P^.Description := ADescription;
  P^.OnHand := AOnHand;
  P^.Price := APrice;
end;
procedure TPriceList.Clear;
begin
  while FRecords.Count > 0 do
  begin
    Dispose(PListEntry(FRecords[FRecords.Count - 1]));
    FRecords.Delete(FRecords.Count - 1);
  end;
end;

C++

// TPriceList
TPriceList::TPriceList()
{
  FRecords = new TList;
}
TPriceList::~TPriceList()
{
  Clear();
  delete FRecords;
}
void TPriceList::Add(String ADescription, int AOnHand, Currency APrice)
{
  ::PListEntry P = new ::TListEntry;
  FRecords->Add(P);
  P->Description = ADescription;
  P->OnHand = AOnHand;
  P->Price = APrice;
}
void TPriceList::Clear()
{
  while (FRecords->Count > 0)
  {
    delete FRecords->Items[FRecords->Count - 1];
    FRecords->Delete(FRecords->Count - 1);
  }
}

The next section shows the implementation of the TUserDataSource class.