Question

help(unicode) prints something like:

class unicode(basestring)
 |  unicode(string [, encoding[, errors]]) -> object
...

but you can use something different from a basestring as argument, you can do unicode(1) and get u’1′. What happens in that call? int don’t have a __unicode__ method to be called.

Answer 1

If __unicode__ exists it is called, otherwise it falls back to __str__

class A(int):
    def __str__(self):
        print "A.str"
        return int.__str__(self)

    def __unicode__(self):
        print "A.unicode"
        return int.__str__(self)

class B(int):
    def __str__(self):
        print "B.str"
        return int.__str__(self)


unicode(A(1)) # prints "A.unicode"
unicode(B(1)) # prints "B.str"