Re: CRC in Ada?

[dewar@merv.cs.nyu.edu (Robert Dewar)]

<<I won't comment on Sequential_IO and Direct_IO, but surely Text_IO is
intended to produce a format that makes sense to non-Ada programs.  That
is, if I write a file using Text_IO, and I don't do anything funny with
control characters, then I ought to be able to read that file into my
favorite text editor (say, Emacs), and have it make sense.  If the Ada
system is putting weird stuff in the file, which makes this impossible,
then that's a bug, IMHO.  (IMHO, the term "bug" refers to any
wrong/undesirable behavior, whether or not it violates the Ada standard.
That is, the set of possible bugs in an Ada compiler is a superset of
the set of possible vilations of the RM.)>>

It is hard to know what Text_IO is intended for sometimes, but the page
mark business means that in fact you have to work VERY hard to make
Text_IO files compatible with interactive IO, or compatible with text
editors, probably any file written by Text_IO can be read by an editor,
but the opposite is not always true.

Also, on a system like the Unisys 1100 operating system, the natural
format for Text_IO files would be the normal source format (I forget
what it is called, a while since I worked with it), but there are aspects
to this format that make it incompatible with Text_IO, so it would not
be surprising to find Text_IO using some other weird format not directly
readable by editors.

Sure on a system with no fancy IO, like Unix, you can easily enough
make Text_IO consistent with editors, but in the case of systems with
complex file structures, it is not a all clear that you can expect
ayutomatic compatibilty bnetween text_IO and some arbitrary editors,
indeed on such systems editorsd are not always compatible with one
another (for examle, one might use a quite different file format for
source files, and general ascii files).