I am learning the ropes in Python. When I try to print an object of class Foobar
using the print()
function, I get an output like this:
<__main__.Foobar instance at 0x7ff2a18c>
Is there a way I can set the printing behaviour (or the string representation) of a class and its objects? For instance, when I call print()
on a class object, I would like to print its data members in a certain format. How to achieve this in Python?
If you are familiar with C++ classes, the above can be achieved for the standard ostream
by adding a friend ostream& operator << (ostream&, const Foobar&)
method for the class.
>>> class Test:
... def __repr__(self):
... return "Test()"
... def __str__(self):
... return "member of Test"
...
>>> t = Test()
>>> t
Test()
>>> print(t)
member of Test
The __str__
method is what happens when you print it, and the __repr__
method is what happens when you use the repr()
function (or when you look at it with the interactive prompt). If this isn't the most Pythonic method, I apologize, because I'm still learning too - but it works.
If no __str__
method is given, Python will print the result of __repr__
instead. If you define __str__
but not __repr__
, Python will use what you see above as the __repr__
, but still use __str__
for printing.