Subclassing file class

[David Vaughan]

I'm using v2.3, and trying to write to text files, but with a maximum
line length.  So, if a line is getting too long, a suitable ' '
character is replaced by a new line.  I'm subclassing the file class,
and, as long as I just use the write method, this works fine.  But
"print >>" doesn't behave as I want:

class max_width_file(file):
    def write(self, txt):
        print "In max_width_file's write method."
fout = max_width_file('foo.txt', 'w')
print >> fout, 'bar'
fout.close()

bypasses my write method and prints 'bar' directly to the file.  That
isn't the behaviour I inferred from

http://docs.python.org/ref/print.html

How do I intercept "print >>"?  Has anyone already implemented this?
And should the documentation be changed?

Any help very welcome.
David



David Vaughan
Structural Analyst
for Gifford

GIFFORD AND PARTNERS LTD
Carlton House, Ringwood Road, Woodlands,
Southampton, SO40 7HT,  UNITED KINGDOM
 
Tel: +44 (0)23 8081 7500      Fax: +44 (0)23 8081 7600
Email: David.Vaughan at gifford.uk.com
Web:  http://www.gifford.uk.com

This e-mail and any files transmitted with it are intended solely for
the use of the individual or entity to whom they are addressed and may
be confidential.  If you are not the intended recipient or the person
responsible for delivering the e-mail to the intended recipient, be
advised that you have received this e-mail in error and that any use,
dissemination, forwarding, printing or copying of this e-mail is
strictly prohibited.