How to print instances of a class using print

0 votes

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.

Nov 20, 2020 in Python by anonymous
• 10,440 points
81 views

4 answers to this question.

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>>> 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.

answered Nov 20, 2020 by Gitika
• 65,870 points
0 votes

You can redefine the __str__ function if it does answer the question 

[edit] that's exactly what your link is talking about 

Image may contain: text that says 'class Foo: def _init_(self): (self): self.val (range list(range(1, (1, 6)) def _str_(self) self): return sum is: f=Foo() print (f) str(sum(self.val)) sum is: 15'

answered Nov 25, 2020 by Fabrice Kinnar
0 votes

It's similar to c++ but a bit easier, no need to have a stream at all, just use a function named __str__ which returns the string you want to print

answered Nov 25, 2020 by Ahmad rayan
0 votes

You need to implement your own __repr__ method for a custom representation of the class object and if you need custom string conversion then implement __str__ method.

answered Nov 25, 2020 by Saksham Azad

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