__future__ in Python
1. from __future__ import xxxx
这是为了在低版本的python中使用可能在某个高版本python中成为语言标准的特性,从而
在将代码由低版本迁移到高版本的过程中,减少需要做的工作。
这种语句被称为 future_statement
2. future_statement的语法定义: Ref[2]
future_statement: "from" "__future__" "import" feature ["as" name] ("," feature ["as" name])* feature: identifier name: identifier
3. 使用future_statement的注意事项
Reference
1. What is __future__ in Python used for and how/when to use it, and how it works
http://stackoverflow.com/questions/7075082/what-is-future-in-python-used-for-and-how-when-to-use-it-and-how-it-works
2. PEP 236 - PEP 236 -- Back to the __future__
https://www.python.org/dev/peps/pep-0236/
3. 28.11. __future__ — Future statement definitions
https://docs.python.org/2/library/__future__.html
4. Supporting Python 2 and 3 without 2to3 conversion
http://python3porting.com/noconv.html (Porting to Python 3)
http://pypi.python.org/pypi/six
5. http://python-future.org/imports.html (To Read)
包括以下内容:
- absolute_import: PEP 328: Imports: Multi-Line and Absolute/Relative
- division: PEP 238: Changing the Division Operator
- print_function: PEP 3105: Make print a function
- unicode_literals: PEP 3112: Bytes literals in Python 3000
时间: 2024-10-05 04:19:33