taken from www.chami.com
//
// FunctionWithVarArgs()
//
// skeleton for a function that
// can accept vairable number of
// multi-type variables
//
// here are some examples on how
// to call this function:
//
// FunctionWithVarArgs(
// [ 1, True, 3, '5', '0' ] );
//
// FunctionWithVarArgs(
// [ 'one', 5 ] );
//
// FunctionWithVarArgs( [] );
//
procedure FunctionWithVarArgs(
const ArgsList : array of const );
var
ArgsListTyped :
array[0..$FFF0 div SizeOf(TVarRec)]
of TVarRec absolute ArgsList;
n : integer;
begin
for n := Low( ArgsList ) to
High( ArgsList ) do
begin
with ArgsListTyped[ n ] do
begin
case VType of
vtInteger : begin
{handle VInteger here} end;
vtBoolean : begin
{handle VBoolean here} end;
vtChar : begin
{handle VChar here} end;
vtExtended : begin
{handle VExtended here} end;
vtString : begin
{handle VString here} end;
vtPointer : begin
{handle VPointer here} end;
vtPChar : begin
{handle VPChar here} end;
vtObject : begin
{handle VObject here} end;
vtClass : begin
{handle VClass here} end;
vtWideChar : begin
{handle VWideChar here} end;
vtPWideChar : begin
{handle VPWideChar here} end;
vtAnsiString: begin
{handle VAnsiString here} end;
vtCurrency : begin
{handle VCurrency here} end;
vtVariant : begin
{handle VVariant here} end;
else begin
{handle unknown type here} end;
end;
end;
end;
end;Packed RecordsPacked records is a way to align Delphi records. Delphi variables usually aligned at 2, 4, or 8 byte to optimize access, to make things clear, take a look at following code (taken from delphibasic.co.uk)
type
// Declare an unpacked record
TDefaultRecord = Record
name1 : string[4];
floater : single;
name2 : char;
int : Integer;
end;
// Declare a packed record
TPackedRecord = Packed Record
name1 : string[4];
floater : single;
name2 : char;
int : Integer;
end;
var
defaultRec : TDefaultRecord;
packedRec : TPackedRecord;
begin
ShowMessage('Default record size = '+IntToStr(SizeOf(defaultRec)));
ShowMessage('Packed record size = '+IntToStr(SizeOf(packedRec)));
end;there is more advanced usage for the record type of delphi, such as this one :type
TRect = packed record
case Integer of
0: (Left, Top, Right, Bottom: Integer);
1: (TopLeft, BottomRight: TPoint);
end; TRect.TopLeft will map to the TRect.Left and TRect.Top, TRect.BottomRight will map to the TRect.Right and TRect.Bottom, anoher usage would be like this one :type
// Declare a fruit record using case to choose the
// diameter of a round fruit, or length and height ohterwise.
TFruit = Record
name : string[20];
Case isRound : Boolean of // Choose how to map the next section
True :
(diameter : Single); // Maps to same storage as length
False :
(length : Single; // Maps to same storage as diameter
width : Single);
end;when isRound is true, you could define 1 more variable, and that is the diameter:Single, and if isRound is false, you could define 2 more variable, that is length, and width
