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From: hpoppe@ncar.ucar.edu (Herb Poppe)
Newsgroups: comp.sys.mac.programmer
Subject: Type cast problem in TP 3.0
Message-ID: <11271@ncar.ucar.edu>
Date: 2 May 91 22:00:41 GMT
Sender: news@ncar.ucar.edu
Distribution: na
Organization: National Center for Atmospheric Research
Lines: 38

The TP 3.0 program below illustrates a problem I am having with type 
casting that is driving me nuts. A set of 0..7 has a size of 1. A 
SignedByte has a size of 1. Yet when I type cast the set of 0..7 to a 
SignedByte the compiler complains that:

"Expression can't be cast to the specified type."

How do I interpret the bits in a set of 0..7 as a byte?

-----------------

program SetTest;

 type
  EightBits = (bit0, bit1, bit2, bit3, bit4, bit5, bit6, bit7);
  Port = set of EightBits;

 var
  dataSize: Integer;
  byteSize: Integer;
  portData: Port;
  portByte: SignedByte;

begin

 dataSize := sizeof(portData);      { = 1 }
 byteSize := sizeof(portByte);      { = 1 }
 portData := [bit0, bit7];

 portByte := SignedByte(portData);  {Expression can't be cast to the 
specified type.}

end.

Herb Poppe             hpoppe@ncar.ucar.edu
NCAR                      (303) 497-1296
1850 Table Mesa Dr.
Boulder, CO  80307-3000