delphi - 删除 TList<> 项后如何正确释放内存？

Question

使用TList作为记录容器。在应用过程中，TList添加和删除大量记录。但在delete之后，属性capacity永远不会减少，内存也不会被释放。怎么解决这个问题呢？简单的代码示例:

type
  TMyRecord = record
    Num : integer;
    Str : String
  end;

var
  MyRecord : TMyRecord;
  MyList :TList<TMyRecord>;



  MyList := TList<TMyRecord>.Create;

  MyRecord.Num := 1;
  MyRecord.Str := 'abc';

  for i := 0 to 63 do
    begin
      MyList.Add(MyRecord);
    end;

  Memo1.Lines.Add('Before deleting');
  Memo1.Lines.Add('Count='+IntToStr(MyList.Count));
  Memo1.Lines.Add('Capacity='+IntToStr(MyList.Capacity));

  for i := 0 to 59 do
    begin
      MyList.Delete(0);
    end;

  MyList.Pack; // Here need to somehow free the memory.

  Memo1.Lines.Add('After deleting');
  Memo1.Lines.Add('Count='+IntToStr(MyList.Count));
  Memo1.Lines.Add('Capacity='+IntToStr(MyList.Capacity));

Answer 1

来自documentation on TList.Pack :

This procedure removes from the list any item of class T with a value that is the default value of T.

您发布的代码表明您似乎认为这会减少列表容量，但这不是目的。

您应该使用的是TList.TrimExcess。 From the docu :

TrimExcess sets Capacity to Count, getting rid of all excess capacity in the list.