Article #15470: FILES OF OBJECT TYPE

 Technical Notes Database

TN470D.txt   FILES OF OBJECT TYPE
Category   :Pascal
Platform    :All
Product    :Turbo Pascal  5.5

Description:
Q. Why can't I make a file of ObjectType?
A. Because by the rules of polymorphism, any descendant of
   ObjectType would be type compatible and be able to be written
   to disk as well. The problem with this is that the descendants
   may be (and usually are) of a larger size than the ObjectType
   itself.  Pascal's file structure require all records to be
   the same size, otherwise, how do you know which size object
   do you read in? For an example on how to do Object disk I/O,
   please see the STREAMS example on the distribution diskettes.


Reference:


7/16/98 4:35:32 PM
 

Last Modified: 01-SEP-99