Meaning of -> in Python

0 votes

I have found something interesting when looking at Python 3.3 grammar specification:

funcdef: 'def' NAME parameters ['->' test] ':' suite

The optional 'arrow' block was absent in Python 2 and I couldn't find any information regarding its meaning in Python 3. It turns out this is correct Python and it's accepted by the interpreter:

def f(x) -> 123:
    return x

Could anyone accustomed with this syntax explain it?

Nov 12, 2018 in Python by findingbugs
• 3,140 points
38 views

1 answer to this question.

0 votes

It's a function annotation.

In more detail, Python 2.x has docstrings, which allow you to attach a metadata string to various types of object. This is amazingly handy, so Python 3 extends the feature by allowing you to attach metadata to functions describing their parameters and return values.

answered Nov 12, 2018 by Priyaj
• 56,520 points

Related Questions In Python

+2 votes
3 answers

what is the practical use of polymorphism in Python?

Polymorphism is the ability to present the ...READ MORE

answered Mar 31, 2018 in Python by anto.trigg4
• 3,420 points
1,319 views
+4 votes
6 answers

Use of "continue" in python

The break statement is used to "break" ...READ MORE

answered Jul 16, 2018 in Python by Omkar
• 67,380 points
131 views
+1 vote
4 answers

Count the frequency of an item in a python list

To count the number of appearances: from collections ...READ MORE

answered Oct 18, 2018 in Python by tinitales
592 views
0 votes
1 answer

How can I compare the content of two files in Python?

Assuming that your file unique.txt just contains ...READ MORE

answered Apr 16, 2018 in Python by charlie_brown
• 7,720 points
93 views
0 votes
1 answer

Crawling after login in Python

You missed a few login data forms, ...READ MORE

answered Sep 7, 2018 in Python by Priyaj
• 56,520 points
327 views
0 votes
1 answer

Crawling after login in Python

You missed a few login data forms, ...READ MORE

answered Sep 14, 2018 in Python by Priyaj
• 56,520 points
35 views
0 votes
1 answer

“stub” __objclass__ in a Python class how to implement it?

You want to avoid interfering with this ...READ MORE

answered Sep 27, 2018 in Python by Priyaj
• 56,520 points
49 views
+1 vote
1 answer

How is raw_input() and input() in python3.x?

raw_input() was renamed to input() so now input() returns the exact string ...READ MORE

answered Oct 30, 2018 in Python by Priyaj
• 56,520 points
39 views
0 votes
1 answer

What is the meaning of “int(a[::-1])” in Python?

Assumming a is a string. The Slice ...READ MORE

answered Aug 27, 2018 in Python by Priyaj
• 56,520 points
70 views
0 votes
2 answers

What are the types of dictionary in python?

There are 4 types of dictionary Empty Integer Mixed Dictionary with ...READ MORE

answered Feb 14 in Python by Shashank
• 1,350 points
53 views