Re: Ada streams

[tmoran@acm.org]

>Maybe I should say a quick word on what a stream is. In practice, a
>stream is a sequence of bytes -- which are called 'octets' formally --
>which comprise the binary representation of one or a sequence of
>variable values. The values can be of any type. The bytes do not
  Ada.Streams gives a standardized way for the designer of an object
to supply "IO" routines for that object.  Thus Bitmap'Write might in
fact create a JPEG compressed version of an in-memory bitmap array.
If a user creates a composite object he automatically gets an IO
routine that will make the necessary calls for the component parts.
Thus given
  type Stereo_Image_Type is record
    Left, Right : Bitmap;
  end record;
Stereo_Image_Type'Write(F,Scene); will automatically call Bitmap'Write
on the Left and Right images (unless overridden, of course).
  Ada.Streams does not require you to use Ada.Streams.Stream_IO, however,
so you can also create specialized children of Root_Stream_Type which
don't do IO, but rather something else.  You might just want the
Stream_Element_Count of the size of the object, or perhaps a checksum of
its Stream_Element_Array representation.