Question

In the multiple choice question I’m stucked in, there are three options.
Here goes the question:

Which of the following is a definition of the _str_method?

1. def __str__(self):
      print "(%s, %s, %s)" % (self._n, self._p, self._b)

2. def __str__(self):
      return "(%s, %s, %s)" % (self._n, self._p, self._b)

3. Both

I tested both of them, and both worked, but it is said that (2) is the answer.

The answers of all other similar questions also say that the function with ‘print’ is not the right one.

Is the answer wrong?

Thanks

Answer 1

From the official documentation (emphasis mine):

object.__str__(self)

Called by the str() built-in function and by the print statement to compute the “informal” string representation of an object. This differs from __repr__() in that it does not have to be a valid Python expression: a more convenient or concise representation may be used instead. The return value must be a string object.

As the first version does not return a string object, it must be wrong.