TMemoryStream 私有变量FSize 访问父类私有变量

最新推荐文章于 2022-02-24 16:20:33 发布

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最新推荐文章于 2022-02-24 16:20:33 发布

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分类专栏： DELPHI

本文链接：https://blog.youkuaiyun.com/cb168/article/details/10079343

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本文详细介绍了Delphi中的TCustomMemoryStream和TMemoryStream类，包括类的属性和方法，如SetCapacity、Clear等，并解释了子类如何访问父类的私有变量。

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TCustomMemoryStream = class(TStream)
  private
    FMemory: Pointer;
    FSize, FPosition: NativeInt;
  protected
    procedure SetPointer(Ptr: Pointer; const Size: NativeInt);
  public
    function Read(var Buffer; Count: Longint): Longint; override;
    function Read(Buffer: TBytes; Offset, Count: Longint): Longint; override;
    function Seek(const Offset: Int64; Origin: TSeekOrigin): Int64; override;
    procedure SaveToStream(Stream: TStream); virtual;
    procedure SaveToFile(const FileName: string);
    property Memory: Pointer read FMemory;
  end; // deprecated 'Use TBytesStream';

{ TMemoryStream }

  TMemoryStream = class(TCustomMemoryStream)
  private
    FCapacity: Longint;
    procedure SetCapacity(NewCapacity: Longint);
  protected
    function Realloc(var NewCapacity: Longint): Pointer; virtual;
    property Capacity: Longint read FCapacity write SetCapacity;
  public
    destructor Destroy; override;
    procedure Clear;
    procedure LoadFromStream(Stream: TStream);
    procedure LoadFromFile(const FileName: string);
    procedure SetSize(NewSize: Longint); override;
    function Write(const Buffer; Count: Longint): Longint; override;
    function Write(const Buffer: TBytes; Offset, Count: Longint): Longint; override;
  end; // deprecated 'Use TBytesStream';

procedure TMemoryStream.Clear;
begin
  SetCapacity(0);
  FSize := 0;
  FPosition := 0;
end;

子类如何访问父类的私有变量

不怪不怪因为它们在同一个单元中，也算是友类了

Delphi当中同单元(Unit)当中就可以访问。
因为在Delphi2007及之后，增加了strict关键字，比如strict private，那样就无法访问了。