如何更新TList中的数据< T>？ [英] How can I update a data in a TList<T>?

问题描述

我有此记录（结构）：

  type 
 THexData = record 
地址：Cardinal ; 
 DataLen：Cardinal; 
数据：string; 
 end; 
  

我已声明此列表：

  HexDataList：TList< THexData> ;; 
  

我填充了一些数据。现在我想扫描ListHexData，有时更新 HexDataList 中的记录的元素。

有可能吗？我如何做？

解决方案

  var 
 Item：THexData; 
 ... 
 for i：= 0 to HexDataList.Count-1 do begin 
 Item：= HexDataList [i]; 
 //更新项目
 HexDataList [i]：= Item; 
 end; 
  

绑定是您要修改 HexDataList [i] code>到位，但你不能。当我使用保存记录的 TList< T> 时，我实际上是子类 TList< T> 将 Items 属性替换为返回指向该项目的指针的属性，而不是该项目的副本。

再次查看我的代码I意识到我实际上不是子类 TList< T> ，因为该类太私人以提取指向底层数据的指针。这可能是一个很好的决定。我实际上做的是实现我自己的通用列表类，并允许我自由返回指针到记录如果需要。

I have this record (structure):

type
    THexData = record            
            Address : Cardinal;
            DataLen : Cardinal;
            Data    : string;    
    end;

And I've declared this list:

HexDataList: TList<THexData>;

I've filled the list with some data. Now I'd like scan ListHexData and sometimes update a element of a record inside HexDataList.

Is it possible? How can I do?

解决方案

var
  Item: THexData;
... 
for i := 0 to HexDataList.Count-1 do begin
  Item := HexDataList[i];
  //update Item
  HexDataList[i] := Item;
end;

The bind is that you would like to modify HexDataList[i] in place, but you can't. When I'm working with a TList<T> that holds records I actually sub-class TList<T> and replace the Items property with one that returns a pointer to the item, rather than a copy of the item. That allows for inplace modification.

EDIT

Looking at my code again I realise that I don't actually sub-class TList<T> because it the class is too private to extract pointers to the underlying data. That's probably a good decision. What I actually do is implement my own generic list class and that allows me the freedom to return pointers to records if needed.

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