Delphi: How to add a different constructor to a descendant?

Question

Update: The example i originally had was kind of complex. Here\'s a simple 8 line example that explains everything in one code block. The following

Answer 1

Another possibility is to write a new constructor with default parameter values where the part of the signature with non-default parameters matches the original constructor in the base class:

type
  TXmlStream = class
  private
    FFileName: string;
  public
    constructor Create(const AFileName: string); virtual;
  end;

  TXhtmlStream = class(TXmlStream)
  private
    FEncoding: TEncoding;
  public
    constructor Create(const AFileName: string; AEncoding: TEncoding = encDefault); reintroduce; virtual;
  end;

constructor TXmlStream.Create(const AFileName: string);
begin
  inherited Create;
  FFileName := AFileName;
end;

constructor TXhtmlStream.Create(const AFileName: string; AEncoding: TEncoding);
begin
  inherited Create(AFileName);
  FEncoding := AEncoding;
end;