6 ms·

Python 3 new features

36 points by kasunh 17y ago

notkidding 17y ago
print(cÃ©sar) Should give arc a run for its money.
masklinn 17y ago
Skip that useless "article" and go straight to the source: Python 3.0 whatsnew http://docs.python.org/3.1/whatsnew/3.0.html http://docs.python.org/3.1/whatsnew/3.0.html Python 3.1 whatsnew http://docs.python.org/3.1/whatsnew/3.1.html http://docs.python.org/3.1/whatsnew/3.1.html They're clearer, more readable, more complete and linkable. No reason to use TFA.
jonursenbach 17y ago
"True division—for example, 1/2 returns .5." This wasn't there previously? Ugh.
- jparise 17y ago
  1/2 used to result in integer division, so it would return 0. In Python 3, integer division is spelled "1//2".
- jodrellblank 17y ago
  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.
  - masklinn 17y ago
    > 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)...
    - mcav 17y ago
      Everything's relative. XP was just released in 2001... that was ages ago. Relatively.
- tvon 17y ago
  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.
  - dreish 17y ago
    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.
    - tvon 17y ago
      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...
- hc 17y ago
  see PEP 238, @ http://www.python.org/dev/peps/pep-0238/ http://www.python.org/dev/peps/pep-0238/

36 points by kasunh 17y ago

print(cÃ©sar) Should give arc a run for its money.

Skip that useless "article" and go straight to the source: Python 3.0 whatsnew http://docs.python.org/3.1/whatsnew/3.0.html http://docs.python.org/3.1/whatsnew/3.0.html Python 3.1 whatsnew http://docs.python.org/3.1/whatsnew/3.1.html http://docs.python.org/3.1/whatsnew/3.1.html They're clearer, more readable, more complete and linkable. No reason to use TFA.

jonursenbach 17y ago

"True division—for example, 1/2 returns .5." This wasn't there previously? Ugh.

jparise 17y ago
1/2 used to result in integer division, so it would return 0. In Python 3, integer division is spelled "1//2".
jodrellblank 17y ago
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.
- masklinn 17y ago
  > 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)...
  - mcav 17y ago
    Everything's relative. XP was just released in 2001... that was ages ago. Relatively.
tvon 17y ago
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.
- dreish 17y ago
  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.
  - tvon 17y ago
    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...
hc 17y ago
see PEP 238, @ http://www.python.org/dev/peps/pep-0238/ http://www.python.org/dev/peps/pep-0238/