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pythonstringunicodepython-2.xconventions

__str__ versus __unicode__

Is there a Python convention for when you should implement __str__() versus __unicode__()? I've seen classes override __unicode__() more frequently than __str__() but it doesn't appear to be consistent. Are there specific rules when it is better to implement one versus the other? Is it necessary/good practice to implement both?

Solution

  • __str__() is the old method -- it returns bytes. __unicode__() is the new, preferred method -- it returns characters. The names are a bit confusing, but in 2.x we're stuck with them for compatibility reasons. Generally, you should put all your string formatting in __unicode__(), and create a stub __str__() method:

    def __str__(self):
    return unicode(self).encode('utf-8')

    In 3.0, str contains characters, so the same methods are named __bytes__() and __str__(). These behave as expected.