python 3.3 repr

From	Robin Becker <robin@reportlab.com>
Subject	python 3.3 repr
Date	2013-11-15 11:28 +0000
Newsgroups	comp.lang.python
Message-ID	<mailman.2646.1384514912.18130.python-list@python.org> (permalink)

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I'm trying to understand what's going on with this simple program

if __name__=='__main__':
	print("repr=%s" % repr(u'\xc1'))
	print("%%r=%r" % u'\xc1')

On my windows XP box this fails miserably if run directly at a terminal

C:\tmp> \Python33\python.exe bang.py
Traceback (most recent call last):
   File "bang.py", line 2, in <module>
     print("repr=%s" % repr(u'\xc1'))
   File "C:\Python33\lib\encodings\cp437.py", line 19, in encode
     return codecs.charmap_encode(input,self.errors,encoding_map)[0]
UnicodeEncodeError: 'charmap' codec can't encode character '\xc1' in position 6: 
character maps to <undefined>

If I run the program redirected into a file then no error occurs and the the 
result looks like this

C:\tmp>cat fff
repr='┴'
%r='┴'

and if I run it into a pipe it works as though into a file.

It seems that repr thinks it can render u'\xc1' directly which is a problem 
since print then seems to want to convert that to cp437 if directed into a terminal.

I find the idea that print knows what it's printing to a bit dangerous, but it's 
the repr behaviour that strikes me as bad.

What is responsible for defining the repr function's 'printable' so that repr 
would give me say an Ascii rendering?
-confused-ly yrs-
Robin Becker

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python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 11:28 +0000
  Re: python 3.3 repr Ned Batchelder <ned@nedbatchelder.com> - 2013-11-15 03:38 -0800
    Re: python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 12:16 +0000
      Re: python 3.3 repr Ned Batchelder <ned@nedbatchelder.com> - 2013-11-15 05:54 -0800
        Re: python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 14:29 +0000
        Re: python 3.3 repr Serhiy Storchaka <storchaka@gmail.com> - 2013-11-15 16:40 +0200
        Re: python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 14:52 +0000
    Re: python 3.3 repr Roy Smith <roy@panix.com> - 2013-11-15 09:25 -0500
    Re: python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 14:43 +0000
      Re: python 3.3 repr Ned Batchelder <ned@nedbatchelder.com> - 2013-11-15 07:08 -0800
        Re: python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 15:39 +0000
        Re: python 3.3 repr Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-11-15 16:49 +0100
        Re: python 3.3 repr Chris Angelico <rosuav@gmail.com> - 2013-11-16 03:01 +1100
          Re: python 3.3 repr Neil Cerutti <neilc@norwich.edu> - 2013-11-15 17:47 +0000
            Re: python 3.3 repr Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-16 01:09 +0000
      Re: python 3.3 repr Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-15 17:10 +0000
        Re: python 3.3 repr Chris Angelico <rosuav@gmail.com> - 2013-11-16 04:29 +1100
        Re: python 3.3 repr Cousin Stanley <cousinstanley@gmail.com> - 2013-11-15 10:45 -0700
    Re: python 3.3 repr Joel Goldstick <joel.goldstick@gmail.com> - 2013-11-15 09:50 -0500
    Re: python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 15:03 +0000
    Re: python 3.3 repr Joel Goldstick <joel.goldstick@gmail.com> - 2013-11-15 10:07 -0500
    Re: python 3.3 repr Chris Angelico <rosuav@gmail.com> - 2013-11-16 02:08 +1100
    Re: python 3.3 repr Robin Becker <robin@reportlab.com> - 2013-11-15 15:18 +0000
    Re: python 3.3 repr Roy Smith <roy@panix.com> - 2013-11-15 10:32 -0500
    Re: python 3.3 repr William Ray Wing <wrw@mac.com> - 2013-11-15 11:30 -0500
    Re: python 3.3 repr Zero Piraeus <z@etiol.net> - 2013-11-15 14:06 -0300
    Re: python 3.3 repr Chris Angelico <rosuav@gmail.com> - 2013-11-16 04:11 +1100
    Re: python 3.3 repr Serhiy Storchaka <storchaka@gmail.com> - 2013-11-15 19:37 +0200
  Re: python 3.3 repr Gene Heskett <gheskett@wdtv.com> - 2013-11-15 11:36 -0500
  Re: python 3.3 repr Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-11-15 17:58 +0000
  Re: python 3.3 repr Gene Heskett <gheskett@wdtv.com> - 2013-11-15 14:23 -0500

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