[Python-Dev] New lines, carriage returns, and Windows

[Nick Maclaren]

skip at pobox.com wrote:
> 
> I've been thinking about this some more (in lieu of actually writing up any
> sort of proposal ;-) and I'm not so sure it would be all that useful.  If
> you've opened a file in text mode you should only be writing newlines as
> '\n' anyway.  If you want to translate a text file imported from another
> system to use the current system's line ending just open both the input and
> output files in text mode.

I.e. at least \r, \f and \v are discouraged - i.e. system-dependent,
at best.  That works.

> With universal newlines mode for output, should writing '\r\n' result in one
> or two newlines (or one-and-a-half)?  Depending on the platform you can
> argue that it should write out '\r\r', '\r\n\r\n' or '\n\n' or if on Windows
> that it should be left alone as '\r\n'.  There is, of course, the current
> '\r\r\n' behavior as well.  I don't think there's obviously one best answer.

Quite.  And it has nothing to do with the format the outside system
uses - your first question is purely a matter of what the semantics
of the Python program are.  The question applies as much to zOS as
to any of the systems Python supports.

> If you want to do something esoteric, open the file in binary mode and do
> whatever you like.

Er, no.  That's the Unix mistake.  It works, provided two things are
true:

    1) You don't need to write portable formatting.

    2) The 'outside system' uses the control characters of a byte
stream for formatting.

Let's skip (1) - but (2) is universally true, nowadays, isn't it?
Er, no.  Consider reading and writing to an X window (NOT an xterm).
Such formatting is out-of-band (sorry, I used out-of-bound in a
previous posting).

Ouch.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:  nmm1 at cam.ac.uk
Tel.:  +44 1223 334761    Fax:  +44 1223 334679