Mega Code Archive
TStringList implementing Integers[] array property
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Title: TStringList implementing Integers[] array property
Question: I often store integer values in the Objects[] array property of a TStringList. This involves type casting the integer value as a TObject for the method AddObject() or Objects[] array and back to integer when accessing the Objects array. The following example demonstrates what I mean ...
var oList : TStringList;
oList := TStringList.Create;
oList.AddObject(sSomeString,TObject(iSomeInteger));
// or
oList.Objects[iIndex] := TObject(iSomeInteger);
iSomeInteger := integer(oList.Objects[iIndex]);
This starts to become monotonous when used extensively. I wanted functionality to be able to access this array as plain integers eg. the above becomes ....
var oList : TStringListEx;
oList := TStringListEx.Create;
oList.AddInteger(sSomeString,iSomeInteger);
// or
oList.Integers[iIndex] := iSomeInteger;
iSomeInteger := oList.Integers[iIndex];
The following class extension shows how to implement this by adding a method and a new array property to the Stringlist class. This also demonstrates that various array properties can be created in this class that access the Objects[] array as different types (Boolean,TColor etc.)
Answer:
unit ClassesEx;
interface
uses Classes;
// ==========================================================================
// Class Extensions of STD Delphi Classes
//
// TStringListEx - Extended Stringlist Class
// - Extended to access Objects[] array as integer instead of
// - having to type cast TObject() and integer() repeatedly.
// - function AddInteger(StringValue,IntegerValue)
// - array property Integers[Index]
//
// Mike Heydon 2005
// ==========================================================================
type
{TStringListEx}
TStringListEx = class(TStringList)
private
procedure SetInteger(AIndex,AValue : integer);
function GetInteger(AIndex : integer) : integer;
public
function AddInteger(const AString : string;
AInteger : integer) : integer;
property Integers[AIndex : integer] : integer read GetInteger
write SetInteger;
end;
// --------------------------------------------------------------------------
implementation
{TStringListEx}
// ===================================================
// Get:Set Methods for array proprty Integers
// ===================================================
procedure TStringListEx.SetInteger(AIndex,AValue : integer);
begin
Objects[AIndex] := TObject(AValue);
end;
function TStringListEx.GetInteger(AIndex : integer) : integer;
begin
Result := integer(Objects[AIndex]);
end;
// ========================================================
// Method to add integers like AddObject adds objects
// ========================================================
function TStringListEx.AddInteger(const AString : string;
AInteger : integer) : integer;
begin
Result := AddObject(AString,TObject(AInteger));
end;
end.
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