__future__ in Python

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1. from __future__ import xxxx

這是為了在低版本的python中使用可能在某個高版本python中成為語言標準的特性，從而

在將代碼由低版本遷移到高版本的過程中，減少需要做的工作。

這種語句被稱為?future_statement?

2. future_statement的語法定義: Ref[2]

future_statement: "from" "__future__" "import" feature ["as" name]("," feature ["as" name])*feature: identifiername: identifier

3. 使用future_statement的注意事項

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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)

包括以下內容:?

• 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

轉載于:https://www.cnblogs.com/cwgk/p/4446090.html

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