%r

Peter Hansen peter at engcorp.com
Mon Mar 6 18:00:37 CET 2006


Blackbird wrote:
> I'm trying to get a complete grip on %r.  Is it true that the two programs
> 
> a = '*anything the parser accepts*'
> print '%r' % a
> 
> vs.
> 
> a = r'*anything the parser accepts*'
> print "'%s'" % a
> 
> always produce the same output, where *anything the parser accepts* can be
> replaced with, well, anything the parser accepts?

"Always produce the same output?"  Well, hardly, as even a token test 
proves:

 >>> a = 'testing\'this'
 >>> print '%r' % a
"testing'this"
 >>> b = r'testing\'this'
 >>> print "'%s'" % b
'testing\'this'


Do you realize that '%r' % a just outputs whatever repr(a) returns?  And 
that '%s' % a just outputs whatever str(a) returns?

-Peter




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