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TList抛出异常

发布于 2025-01-14 10:48:38 字数 3607 浏览 0 评论 0原文

我有以下代码：

program Tlist;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  TMyItem = class(TInterfacedObject)
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;

begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
end.

执行时，它会抛出链接到 TList 的异常。

由于 TList 实现了引用计数，并且所有类均派生自 TInterfacedObject 我的印象是内存会自动释放，但显然，我错了。

我做错了什么？

编辑

根据建议，我想出了以下代码：

program Tlist2;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  IMyItem = interface
    ['{2EB53CC3-E5FC-474B-A162-30BBD2D17C48}']
  end;

  TMyItem = class(TInterfacedObject, IMyItem )
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
    destructor Destroy; override;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

destructor TMyList.Destroy;
var
  I: Integer;
  a: Integer;
begin
  for I := 0 to Length(FList) - 1 do
  begin
    if FList[I].Count > 0 then
    begin
      for a := 0 to FList[I].Count - 1 do
      begin
        FList[I][a].Destroy
      end;
    end;
    FList[I].Destroy;
  end;
  inherited;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;


begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
end.

工作正常，不再有内存泄漏，但我觉得我在这里错过了一些东西。 我认为通过使用接口并从 TInterfacedObject 派生我的类，销毁器就不是必需的了。

原文

I have the following code:

program Tlist;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  TMyItem = class(TInterfacedObject)
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;

begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
end.

When executed, it throws an exception linked to TList<T>.

As TList implements the reference counting and all the classes are derived from TInterfacedObject I was under the impression that the memory would be released automatically but obviously, I am wrong.

What am I doing wrong?

EDIT

Following the suggestions I came up with the following code:

program Tlist2;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  IMyItem = interface
    ['{2EB53CC3-E5FC-474B-A162-30BBD2D17C48}']
  end;

  TMyItem = class(TInterfacedObject, IMyItem )
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
    destructor Destroy; override;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

destructor TMyList.Destroy;
var
  I: Integer;
  a: Integer;
begin
  for I := 0 to Length(FList) - 1 do
  begin
    if FList[I].Count > 0 then
    begin
      for a := 0 to FList[I].Count - 1 do
      begin
        FList[I][a].Destroy
      end;
    end;
    FList[I].Destroy;
  end;
  inherited;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;


begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
end.

That works fine, no more memory leaks BUT I am under the impression that I am missing out on something here.
I thought that by using interfaces and deriving my classes from TInterfacedObject the destroyer would not be necessary.

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热风软妹 2025-01-21 10:48:38

根据 David 和 Remi 的意见，我修改了我的代码：

program Tlist3;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  IMyItem = interface
    ['{2EB53CC3-E5FC-474B-A162-30BBD2D17C48}']
  end;

  TMyItem = class(TInterfacedObject)
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TObjectList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
    destructor Destroy; override;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

destructor TMyList.Destroy;
var
  I: Integer;
  a: Integer;
begin
  if Length(FList) > 0 then
  begin
    for I := 0 to Length(FList) - 1 do
    begin
      FList[I].Free;
    end;
  end;
  inherited;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  if Length(FList) > 0 then
  begin
    for I := 0 to Length(FList) - 1 do
    begin
      FList[I].Free;
    end;
  end;
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TObjectList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;


begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
  mylist.Add(2000, 2);
  MyList.Reset(2);
  mylist.Add(1000, 0);
  mylist.Add(2000, 1);
end.

没有内存泄漏。

Following the input from David and Remi I have amended my code:

program Tlist3;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  madExcept,
  madLinkDisAsm,
  madListHardware,
  madListProcesses,
  madListModules,
  System.Generics.Collections,
  System.SysUtils;

type
  IMyItem = interface
    ['{2EB53CC3-E5FC-474B-A162-30BBD2D17C48}']
  end;

  TMyItem = class(TInterfacedObject)
  private
    ItemPrice: Currency;
  public
    constructor Create(const aItemPrice: Currency); reintroduce;
  end;

  IMyList = interface
    ['{1D11BD29-5C1E-4171-B67E-FB9157DCB021}']
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
  end;

  TMyList = class(TInterfacedObject, IMyList)
  private
    FList: array of TObjectList<TMyItem>;
  public
    function Reset(const aItems: Integer): Integer;
    function Add(const aPrice, aItemN: Integer): Integer;
    destructor Destroy; override;
  end;

{ TMyList }

function TMyList.Add(const aPrice, aItemN: Integer): Integer;
begin
  FList[aItemN].Add(TMyItem.Create(aPrice));
  Result := FList[aItemN].Count;
end;

destructor TMyList.Destroy;
var
  I: Integer;
  a: Integer;
begin
  if Length(FList) > 0 then
  begin
    for I := 0 to Length(FList) - 1 do
    begin
      FList[I].Free;
    end;
  end;
  inherited;
end;

function TMyList.Reset(const aItems: Integer): Integer;
var
  I: Integer;
begin
  if Length(FList) > 0 then
  begin
    for I := 0 to Length(FList) - 1 do
    begin
      FList[I].Free;
    end;
  end;
  SetLength(FList, 0);
  SetLength(FList, aItems);
  for I := 0 to Length(FList) - 1 do
  begin
    FList[I] := TObjectList<TMyItem>.Create;
  end;
  Result := Length(FList);
end;

{ TMyItem }

constructor TMyItem.Create(const aItemPrice: Currency);
begin
  ItemPrice := aItemPrice;
end;

var
  MyList: IMyList;


begin
  MyList := TMyList.Create;
  MyList.Reset(3);
  mylist.Add(1000, 1);
  mylist.Add(2000, 2);
  MyList.Reset(2);
  mylist.Add(1000, 0);
  mylist.Add(2000, 1);
end.

No memory leaks.

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