TCustomExpressionParser.DefineFunction

public function TCustomExpressionParser.DefineFunction(

  const AFunctName: AnsiString;

  const AShortName: AnsiString;

  const ADescription: AnsiString;

  const ATypeSpec: AnsiString;

  AMinFunctionArg: Integer;

  AResultType: TExpressionType;

  AFuncAddress: TExprFunc

):TExprWord;