THandleStream

[Properties (by Name)][Methods (by Name)][Events (by Name)]

Base class for streams that are identified by an OS handle.

Declaration

Source position: classesh.inc line 1165

Type
  THandleStream = class (TStream)
  private
    FHandle : THandle;
  protected
    procedure SetSize(NewSize: LongInt);  Override;
    procedure SetSize(const NewSize: Int64);  Override;
  public
    constructor Create(AHandle: THandle);
    function Read(var Buffer; Count: LongInt) : LongInt;  Override;
    function Write(const Buffer; Count: LongInt) : LongInt;  Override;
    function Seek(const Offset: Int64; Origin: TSeekOrigin) : Int64
                 ;  Override;
    Handle : THandle;
  end
  ;

Description

THandleStream is an abstract descendant of the TStream class that provides methods for a stream to handle all reading and writing to and from a handle, provided by the underlying OS. To this end, it overrides the Read and Write methods of TStream.

Remark

ThandleStream does not obtain a handle from the OS by itself, it just handles reading and writing to such a handle by wrapping the system calls for reading and writing; Descendant classes should obtain a handle from the OS by themselves and pass it on in the inherited constructor. Contrary to Delphi, no seek is implemented for THandleStream, since pipes and sockets do not support this. The seek is implemented in descendant methods that support it. !!!

Members

Member	Type	Visibility	Description
Create	Method	public	Create a handlestream from an OS Handle.
FHandle	Field	private
Handle	Property	public	The OS handle of the stream.
Read	Method	public	Overrides standard read method.
Seek	Method	public	Overrides the Seek method.
SetSize	Method	protected
Write	Method	public	Overrides standard write method.

Inheritance

Class	Description
THandleStream	Base class for streams that are identified by an OS handle.

See also

Name	Description
TFileStream	Stream that stores its data in a named file on disk.
THandle	Type to manage streams.
THandle	Type to manage streams.
TStream	Base class for streams.

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