My question is whether or not there are situations in which sys.stdout.write() is preferable to print. Such as it having better performance or resulting in code that makes more sense.
+1
A:
In 2.x, the print statement preprocesses what you give it, turning it into strings along the way, handling separators and newlines, and allowing redirection to a file. 3.x turns it into a function, but it still has the same responsibilities.
sys.stdout is a file or file-like that has methods for writing to it which take strings or something along that line.
Ignacio Vazquez-Abrams
2010-07-16 09:59:50
+1
A:
"print" first converts the object to a string (if it is not already a string). It will also put a space before the object if it is not the start of a line and a newline character at the end.
When using stdout, you need to convert the object to a string yourself (by calling "str", for example) and there is no newline character.
So
print 99
is equivalent to:
import sys
sys.stdout.write(str(99) + '\n')
dogbane
2010-07-16 10:03:21
+1 for mentioning the newline character! This is the main difference between `print` and `.write()`, I'd say.
EOL
2010-07-16 14:19:41
+9
A:
print is just a thin wrapper that formats the inputs and calls the write function of a given object. By default this object is sys.stdout but you can pass a file for example:
print >> open('file.txt', 'w'), 'Hello', 'World', 2+3
In Python 3.x, print becomes a function but it is still possible to pass something else than sys.stdout. see http://docs.python.org/library/functions.html.
in Python 2.6+, print is still a statement but can be used as a function with from __future__ import print_function
luc
2010-07-16 10:06:41
print is still a statement in Python 2.7. It can be turned into a function by using `from __future__ import print_function`, but this was already supported in Python 2.6.
lunaryorn
2010-07-16 11:09:58
It's also worth noting that `print` also appends a newline to whatever you write which doesn't happen with `sys.stdout.write`.
Michael Mior
2010-07-16 11:49:48
@Michael Mior: True, I've said that "it formats the inputs". Better answser would mention what kind of formatting. Thanks for clarification.
luc
2010-07-16 13:35:00
A:
My question is whether or not there are situations in which sys.stdout.write() is preferable to print
After finishing developing a script the other day I uploaded it to a Unix server, all my debug messages were print statements and these do not appear on a server log, so this is an example of a case where you may need to use sys.stdout.write.
LiamSullivan
2010-07-16 10:59:15