On Sat, Jul 23, 2011 at 7:48 AM, amt <0101...@gmail.com> wrote: > Hello! I'm having troubles understanding what is the difference between %s > and %r(format characters). I did google and found something on > StackOverflow but I don't understand the explanation as it's not beginner > orientated. > > > Also, I have this code from learn python the hard way. Why at line 9 does > he uses %r? Why did he didn't wrote print "I said: %s." %x ? > <snip>
As the answer here ( http://stackoverflow.com/questions/6005159/when-to-use-r-instead-of-s-in-python) says, it changes the method of evaluating an object. Here's a simple example: In [2]: class Thingy: ...: def __str__(self): ...: return "Hello" ...: def __repr__(self): ...: return "Goodbye" ...: ...: In [3]: "%s %r" % (Thingy(), Thingy()) Out[3]: 'Hello Goodbye' I'm not sure if there's a huge difference, and to be honest usually my classes look like this: class CoolGuy: def __str__(self): return "I'm a cool guy" def __repr__(self): return str(self) so there would be no difference between the two. In the interpreter, the __repr__ method is called on the class when you type it in - that's how python knows what to display: In [5]: cool = Thingy() In [6]: cool Out[6]: Goodbye Classes also start out with a default __repr__ that contains... well, this: In [7]: class AnotherThingy: ...: pass ...: In [8]: neat = AnotherThingy() In [9]: neat Out[9]: <__main__.AnotherThingy instance at 0x9a5a66c> HTH, Wayne
_______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
