Programming Forums > Script Programming > Python

Dietrich · Apr 15th, 2006, 5:16 AM

Some interesting stuff has been added.

If you are interested in the changes, got to:
http://docs.python.org/dev/whatsnew/whatsnew25.html

Sane · Apr 15th, 2006, 9:56 AM

This is one part they added: http://docs.python.org/dev/whatsnew/node3.html

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x = true_value if condition else false_value

And what was wrong with:

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x = (true_value, false_value)[x==False]

Geez...

Kakao · Apr 16th, 2006, 7:59 AM

Quote:

Originally Posted by Sane

This is one part they added: http://docs.python.org/dev/whatsnew/node3.html

(Toggle Plain Text)

x = true_value if condition else false_value

And what was wrong with:

(Toggle Plain Text)

x = (true_value, false_value)[x==False]

Geez...

Yes, an indexed tuple is very convenient as well. But note that a true condition returns the second tuple element and not the first as would be more natural:

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x = (a, b)[True] # x = b
x = (a, b)[False] # x = a

The proposed sintax address it making the true value come first. In your example you had to do a NOT(condition) to make it work the same.

Sane · Apr 16th, 2006, 10:38 AM

Quote:

Originally Posted by Kakao

The proposed sintax address it making the true value come first. In your example you had to do a NOT(condition) to make it work the same.

Not quite. I've noticed Python can be quite finicky about that. I don't have any examples, but I've remembered times when certain objects/items have been considered "not False" but not "True". Therefore we must use "not False" to withstand all the possible cases.

Jessehk · Apr 15th, 2006, 10:00 AM

A few things are clearly taken from Ruby.

Especially this: http://docs.python.org/dev/whatsnew/node10.html

Which are basically copying Ruby blocks:

Ruby

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File.open("test.txt", 'r') do |file|
    #do stuff with file
    #automatically closed
end

Python in 2.5

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with open("test.txt", 'r') as f:
    for line in f:
        print line    
 
   #do stuff with file
   #automatically closed

But Ruby has copied plenty of things from Python, so it is not necessarily a bad thing. Just interesting...

Arevos · Apr 15th, 2006, 10:41 AM

Quote:

Originally Posted by Jessehk

Which are basically copying Ruby blocks

No, they're not. Although they can be used in similar ways, Python's with statement is different in implementation.

For instance, the file open code you had in Ruby, would translate to this in Python:

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def file_stuff(file):
    #do stuff with file
    #automatically closed
ruby_style_open("test.txt", 'r', file_stuff)

Whilst the Python with statement translates so:

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file = open("test.txt", 'r')
file.__enter__()
#do stuff with file
#automatically closed
file.__exit__()

See the difference?

Quote:

Originally Posted by Sane

They also added any() and all(). I still stick with my opinion that it's not only redundant, but slower...

Uh... Why would it be slower? Presumably, any and all are just wrappers around "True in" and "False not in".

I kind of like these wrappers. In my opinion, they make things a little neater and easier to read:

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if False not in (x < 10 for x in numbers):
    print "All numbers below ten"

if all(x < 10 for x in number):
    print "All numbers below ten"

Personally, I'm all looking forward to Python's continuation support

Sane · Apr 15th, 2006, 10:04 AM

Quote:

The net result of the 2.5 optimizations is that Python 2.5 runs the pystone benchmark around XXX% faster than Python 2.4.

Lame... T__T

They also added any() and all(). I still stick with my opinion that it's not only redundant, but slower...

(Toggle Plain Text)

# 2.4 "any"
if True in (0, 1, 2, 3, 4):
    print "Any"

# 2.5 "any"
if any((0, 1, 2, 3, 4)):
    print "Any"

# 2.4 "all"
if not False in (1, 2, 3, 4, 5):
    print "All"

# 2.5 "all"
if all((1, 2, 3, 4, 5)):
    print "All"

Apr 15th, 2006, 5:16 AM	#1
Dietrich Professional Programmer Join Date: Feb 2005 Posts: 434 Rep Power: 4	Python 2.5 Some interesting stuff has been added. If you are interested in the changes, got to: http://docs.python.org/dev/whatsnew/whatsnew25.html __________________ I looked it up on the Intergnats!

Apr 15th, 2006, 9:56 AM	#2
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,086 Rep Power: 6	This is one part they added: http://docs.python.org/dev/whatsnew/node3.html (Toggle Plain Text) x = true_value if condition else false_value x = true_value if condition else false_value And what was wrong with: (Toggle Plain Text) x = (true_value, false_value)[x==False] x = (true_value, false_value)[x==False] Geez...

Apr 15th, 2006, 10:00 AM	#5
Jessehk The Oblivious One Join Date: May 2005 Location: Ontario, Canada Posts: 648 Rep Power: 4	A few things are clearly taken from Ruby. Especially this: http://docs.python.org/dev/whatsnew/node10.html Which are basically copying Ruby blocks: Ruby (Toggle Plain Text) File.open("test.txt", 'r') do \|file\| #do stuff with file #automatically closed end File.open("test.txt", 'r') do \|file\| #do stuff with file #automatically closed end Python in 2.5 (Toggle Plain Text) with open("test.txt", 'r') as f: for line in f: print line #do stuff with file #automatically closed with open("test.txt", 'r') as f: for line in f: print line #do stuff with file #automatically closed But Ruby has copied plenty of things from Python, so it is not necessarily a bad thing. Just interesting... __________________ Dr. Zoidberg: [ecstatic] I'm going to a movie... with FRIENDS!

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