Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!lll-lcc!pyramid!athertn!thanh
From: thanh@athertn.Atherton.COM (Thanh Diec)
Newsgroups: comp.lang.c++
Subject: Objectifying contents read in from disk
Message-ID: <7316@athertn.Atherton.COM>
Date: 24 Jul 89 01:26:12 GMT
Reply-To: thanh@athertn.Atherton.COM (Thanh Diec)
Distribution: usa
Organization: Atherton Technology, Sunnyvale, CA
Lines: 44



    After objects are written out to disk, and then read back in again,
possibly by a different program, what does the reader need to do to set the
content read in to behave correctly as objects?  For example, the runtime
_vptr's in the writer program are going to be different from the reader's,
even though both programs include the same ".h".

Writer:

  // write out an array of 1024 objects 

  write(fd, &object_array[0], sizeof(class1) * 1024);

  
Reader:

  read(fd, buf, sizeof(class1) * 1024);
  
  class1 *p1 = (class1 *)buf;		

  // buf is not ready to used as objects yet, must set runtime values
  // such as _vptr's

  for (idx = 0; idx < 1024; idx++)
  {
    // ??? what to here without doing a second copy into a correctly 
    // initialized dummy object.
    
    dummy_obj->member1 = (p1+idx)->member1;
    dummy_obj->member2 = (p1+idx)->member2;
    dummy_obj->member3 = (p1+idx)->member3;
    
  }
    

Thanks in advance,

Thanh Diec
Atherton Technology	(408)734-9822
thanh@atherton.com
{hpda,sun,decwrl}!athertn!thanh