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>>> 3/4
0
>>> from __future__ import division
>>> 3/4
0.75
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| feature | optional in | mandatory in | effect |
|---|---|---|---|
| nested_scopes | 2.1.0b1 | 2.2 | PEP 227: Statically Nested Scopes |
| generators | 2.2.0a1 | 2.3 | PEP 255: Simple Generators |
| division | 2.2.0a2 | 3.0 | PEP 238: Changing the Division Operator |
| absolute_import | 2.5.0a1 | 2.7 | PEP 328: Imports: Multi-Line and Absolute/Relative |
| with_statement | 2.5.0a1 | 2.6 | PEP 343: The “with” Statement |
| print_function | 2.6.0a2 | 3.0 | PEP 3105: Make print a function |
| unicode_literals | 2.6.0a2 | 3.0 | PEP 3112: Bytes literals in Python 3000 |
PEP：Python Enhancement Proposals
可以在这个地方找到很多PEP：http://www.python.org/dev/peps/ 里面还能看到许多提议的动机
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nested_scopes: 改变名空间的搜索过程
generators:使用生成器.能够产生能保存当前状态的函数.
division:精确的除法
absolute_import:包含绝对路径.方便include
with_statement:安全的打开文件
from __future__ import division
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原文地址：http://www.cnblogs.com/wjoyxt/p/4554477.html
