Newsgroups: comp.lang.c++
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!caen!caen.engin.umich.edu!brucew
From: brucew@caen.engin.umich.edu (Bruce Hugh Wilson)
Subject: Reading in objects (of different classes) from a text file
Message-ID: <1991Mar28.195840.19270@engin.umich.edu>
Keywords: cin, file i/o
Sender: news@engin.umich.edu (CAEN Netnews)
Reply-To: brucew@caen.engin.umich.edu (Bruce Hugh Wilson)
Organization: University of Michigan Engineering, Ann Arbor
Date: Thu, 28 Mar 1991 19:58:40 GMT

I'm writing an application which involves inputting/saving/reading (from a
keyboard and text file) objects of different classes, but with a common
parent class.  It's easy enough to write various overloaded << operators
to handle objects of different classes- but this is because the operators
can recognize the class the object belongs to.  A sample file output might
look like:

<motor>
motor1, 3.4, 5.4, .001 ...
<load>
load1, 4.3
<shaft>
big_shaft,10.8,0.1 ...

Is there a way to avoid the use of a switch statement in reading this info in?
My current strategy entails reading <the_identifier> and using a switch
statement, creating an object of the appropriate class, and then reading
in the next line of the file.  Is there a simpler/better way?