Re: Building blocks (Was: Design By Contract)

[Paul Johnson <Paul@treetop.demon.co.uk>]

In article <3432788C.E35@uk.ibm.com>, Paul M Gover
<Paul_Gover@uk.ibm.com> writes

>(One of the while-loop problem is that for a tidy
>record processing program you have to write
>       record = file.read()
>       Do while(~file.eof())
>               thing.accept(record)
>               record = file.read()
>       End while
>)

I know that this was an aside, but it still puzzles me.  Surely it will
be wrong if the file is empty: there will be no record to read.  The
correct version (in Eiffel) would be

   from file.open("foo") until file.eof loop
      thing.accept (file.record)
   end -- loop

If you have to read a dummy record before file.eof becomes valid then
you have a badly designed file object.

Paul.

--------------------------------+---------------------------------
Paul Johnson                    | You are lost in a maze of twisty
Email: Paul@treetop.demon.co.uk | little standards, all different.
       paul.johnson@gecm.com    |