PythonCharmers/python-future

print() behavior change

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#473 opened on Jun 4, 2019

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 (0 comments) (0 reactions) (1 assignee)Python (1,172 stars) (327 forks)batch import
0.19bughelp wanted

Description

$ cat print_failure.py 
print 'foo\n',
print 'bar\n',
$ python print_failure.py | xxd
00000000: 666f 6f0a 6261 720a                      foo.bar.
$ futurize -nw --no-diffs print_failure.py
$ cat print_failure.py 
from __future__ import print_function
print('foo\n', end=' ')
print('bar\n', end=' ')
$ python print_failure.py | xxd
00000000: 666f 6f0a 2062 6172 0a20                 foo. bar.

If the to be printed thing ends with a newline an additional space character is added to the output.

Contributor guide

Tech stack
python
Domain
toolingbackend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic PythonFamiliarity with print function
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate the futurize tool's source code to understand how it transforms print statements. Focus on the logic that adds 'end= ' when the original print ends with a newline. Look for any conditional handling of trailing newlines. The bug is reproducible with the given example, so verify the transformation in the code and propose a fix to ensure no extra space is added when the printed string ends with a newline.