How do I free the contents of a TList?

Question

I have this code in Delphi 4. I created 10 objects of type T_Charge (see below), which I added to a TList, named myList. The T_Charge type has references to three objects of type T_Platte (see below).

What is the correct way of freeing all the memory of all 10 objects? So, for every object I want to free the memory of P1, P2, P3, F_Treated and so on, as well as the memory of myCharge itself. I tried about everything, but keep getting errors.

procedure Test;
var 
  myList: TList;
  myCharge: T_Charge;
begin
  myList := TList.Create;

  for i := 0 to 9 do
  begin;
    myCharge := T_Charge.Create(...);
    myList.Add(myCharge);
  end;
  ...
end;

type
  T_Platte = class(TObject)
  private
    F_Nummer : Integer;
    F_Los    : Integer;
    F_Dicke  : Real;
    F_Lange  : Real;
    F_Breite : Real;
    F_QuenchCode : Integer;
    F_Geschwindigkeit : Real;
    F_Menge  : Integer;
    F_MengeInLos : Integer;
    F_Treated : Boolean;
  public
    constructor Create(inNummer, inLos: Integer; inDicke, inLange, inBreite, inGeschwindigkeit : Real; inQuenchCode,inMenge: Integer; inTreated: Boolean); overload;
    constructor Create(inPlatte: T_Platte); overload;
    destructor Destroy; override;

    property Nummer: Integer read F_Nummer write F_Nummer;
    property Los: Integer read F_Los write F_Los;
    property Dicke: Real read F_Dicke write F_Dicke;
    property Lange: Real read F_Lange write F_Lange;
    property Breite: Real read F_Breite write F_Breite;
    property QuenchCode : Integer read F_QuenchCode write F_QuenchCode;
    property Geschwindigkeit: Real read F_Geschwindigkeit write F_Geschwindigkeit;
    property Menge: Integer read F_Menge write F_Menge;
    property MengeInLos: Integer read F_MengeInLos write F_MengeInLos;
    property Treated: Boolean read F_Treated write F_Treated;

    function getPlattenRecord: string;
  end; // class T_Platte  

  T_Charge = class(TObject)
  private
    F_P1 : T_Platte;
    F_P2 : T_Platte;
    F_P3 : T_Platte;
    F_Treated : Boolean;
    F_Vmin : Real;
    F_Qty : Integer;
    F_RelationNext : Boolean;
  public
    constructor Create(inP1, inP2, inP3 : T_Platte; inTreated: Boolean; inVmin: Real; inQty: Integer; inRelationNext: Boolean);  overload;
    constructor Create(inCharge : T_Charge); overload;
    destructor Destroy; override;

    property P1: T_Platte read F_P1 write F_P1;
    property P2: T_Platte read F_P2 write F_P2;
    property P3: T_Platte read F_P3 write F_P3;
    property Treated : Boolean read F_Treated write F_Treated;
    property Vmin : Real read F_Vmin write F_Vmin;
    property Qty : Integer read F_Qty write F_Qty;
    property RelationNext : Boolean read F_RelationNext write F_RelationNext;

    function getChargeRecord: string;
  end; // class T_Charge


constructor T_Platte.Create(inNummer, inLos: Integer; inDicke, inLange, inBreite, inGeschwindigkeit: Real; inQuenchCode,inMenge: Integer; inTreated: Boolean);
begin
  F_Nummer := inNummer;
  F_Los := inLos;
  F_Dicke := inDicke;
  F_Lange := inLange;
  F_Breite := inBreite;
  F_Geschwindigkeit := inGeschwindigkeit;
  F_QuenchCode := inQuenchCode;
  F_Menge := inMenge;
  F_MengeInLos := 0;
  F_Treated := inTreated;
end;

constructor T_Charge.Create(inP1, inP2, inP3 : T_Platte; inTreated: Boolean; inVmin:  Real; inQty: Integer; inRelatio nNext: Boolean);
begin
  F_P1 := T_Platte.Create(inP1);
  F_P2 := T_Platte.Create(inP2);
  F_P3 := T_Platte.Create(inP3);
  F_Treated := inTreated;
  F_Vmin := inVmin;
  F_Qty := inQty;
  F_RelationNext := inRelationNext;
end;

Answer 1

To free the list objects, create your list and override TList.Notify().

procedure THotFixList.Notify(Ptr: Pointer; Action: TListNotification);
begin
  inherited;
  if Action = lnDeleted then
    Tobject(Ptr).Free;
end;

It will ensure your objects are freed whenever you call TLIst.Delete, TList.Clear, TList.Free, without having to iterate the list yourself each time.