Understanding repr function in Python

0 votes

repr(): evaluatable string representation of an object (can "eval()" it, meaning it is a string representation that evaluates to a Python object)

In other words:

>>> x = 'foo'
>>> repr(x)
"'foo'"

Questions:

  1. Why do I get the double quotes when I do repr(x)? (I don't get them when I do str(x))
  2. Why do I get 'foo' when I do eval("'foo'") and not x which is the object?

Sep 17, 2018 in Python by bug_seeker
• 15,520 points
6,174 views

1 answer to this question.

0 votes
>>> x = 'foo'
>>> x
'foo'

So the name x is attached to 'foo' string. When you call for example repr(x) the interpreter puts 'foo' instead of x and then calls repr('foo').

>>> repr(x)
"'foo'"
>>> x.__repr__()
"'foo'"

repr actually calls a magic method __repr__ of x, which gives the string containing the representation of the value 'foo' assigned to x. So it returns 'foo' inside the string ""resulting in "'foo'". The idea of repr is to give a string which contains a series of symbols which we can type in the interpreter and get the same value which was sent as an argument to repr.

>>> eval("'foo'")
'foo'

When we call eval("'foo'"), it's the same as we type 'foo' in the interpreter. It's as we directly type the contents of the outer string "" in the interpreter.

>>> eval('foo')

Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    eval('foo')
  File "<string>", line 1, in <module>
NameError: name 'foo' is not defined

If we call eval('foo'), it's the same as we type foo in the interpreter. But there is no foo variable available and an exception is raised.

>>> str(x)
'foo'
>>> x.__str__()
'foo'
>>> 

str is just the string representation of the object (remember, x variable refers to 'foo'), so this function returns string.

>>> str(5)
'5'

String representation of integer 5 is '5'.

>>> str('foo')
'foo'

And string representation of string 'foo' is the same string 'foo'.

answered Sep 17, 2018 by Priyaj
• 58,100 points

Related Questions In Python

0 votes
1 answer

What is the use of raw_input function in Python?

raw_input fuction is no longer available in ...READ MORE

answered May 2, 2018 in Python by aayushi
• 750 points
1,234 views
0 votes
1 answer

What does ' -> ' mean in Python function definitions?

It's a function annotation. In more detail, Python 2.x ...READ MORE

answered May 23, 2018 in Python by charlie_brown
• 7,720 points
891 views
0 votes
1 answer

Python: Lambda function in List Comprehensions

The first one create a single lambda ...READ MORE

answered Aug 27, 2018 in Python by Priyaj
• 58,100 points
2,644 views
0 votes
1 answer

Is there a foreach function in python and is there a way to implement it if there isnt any

Every occurence of "foreach" I've seen (PHP, ...READ MORE

answered Aug 31, 2018 in Python by charlie_brown
• 7,720 points
1,119 views
0 votes
2 answers
+1 vote
2 answers

how can i count the items in a list?

Syntax :            list. count(value) Code: colors = ['red', 'green', ...READ MORE

answered Jul 7, 2019 in Python by Neha
• 330 points

edited Jul 8, 2019 by Kalgi 4,398 views
0 votes
1 answer
+1 vote
1 answer

What is the function for Factorial in Python

Easiest way: math.factorial(x) (available in 2.6 and ...READ MORE

answered Aug 21, 2018 in Python by Priyaj
• 58,100 points

edited Aug 21, 2018 by Omkar 1,318 views
+1 vote
1 answer

Understanding Pickling in Python

While others have pointed to the Python ...READ MORE

answered Aug 22, 2018 in Python by Priyaj
• 58,100 points
901 views
webinar REGISTER FOR FREE WEBINAR X
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP