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Python 3 new features

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36 pointskasunh11 comments

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Skip that useless "article" and go straight to the source:

Python 3.0 whatsnew http://docs.python.org/3.1/whatsnew/3.0.html

Python 3.1 whatsnew http://docs.python.org/3.1/whatsnew/3.1.html

They're clearer, more readable, more complete and linkable. No reason to use TFA.

"True division—for example, 1/2 returns .5."

This wasn't there previously? Ugh.

1/2 used to result in integer division, so it would return 0. In Python 3, integer division is spelled "1//2".

It would do so if one of the numbers was a float - 1.0/2.0 gave a float answer, 1/2 gave an integer answer.

It was also possible in recent Python versions to switch this behaviour using "from __future__ import division" so they recognised it as a ward, but it's only with the decision to allow Python 3 to make backwards compatibility breaking changes that it could be changed normally.

> It was also possible in recent Python versions

Not that recent, the switch has been there since 2.2 alpha 2, released 8 years ago (August 22, 2001):

    __all__ = ['all_feature_names', 'nested_scopes', 'generators', 'divisi...
    absolute_import = _Feature((2, 5, 0, 'alpha', 1), (2, 7, 0, 'alpha', 0...
    all_feature_names = ['nested_scopes', 'generators', 'division', 'absol...
    division = _Feature((2, 2, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0), 8192...
    generators = _Feature((2, 2, 0, 'alpha', 1), (2, 3, 0, 'final', 0), 0)
    nested_scopes = _Feature((2, 1, 0, 'beta', 1), (2, 2, 0, 'alpha', 0), ...
    print_function = _Feature((2, 6, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0)...
    unicode_literals = _Feature((2, 6, 0, 'alpha', 2), (3, 0, 0, 'alpha', ...
    with_statement = _Feature((2, 5, 0, 'alpha', 1), (2, 6, 0, 'alpha', 0)...

Everything's relative. XP was just released in 2001... that was ages ago. Relatively.

When given two integers pretty much any language will return an integer (so 1/2 = 0).

In Python 2.6, if one of the arguments is a float you'll get a float result, the same is true for Ruby 1.8.

The new behavior is to return a float even if two integers are passed.

Well, not exactly "pretty much any language": Common Lisp, Scheme, Arc, Clojure, Haskell, Perl, and SQL all return either 1/2 or 0.5. I'm sure there are plenty of others I'm not familiar with that behave the same way.

Good point. I was thinking of the C-based languages, though to be honest I'm not sure all of them behave in the same way. I should have been more careful talking about languages, especially around here...

see PEP 238, @ http://www.python.org/dev/peps/pep-0238/

print(cÃ©sar)

Should give arc a run for its money.

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