以与python2和python3兼容的方式将字节写入标准输出 [英] Writing bytes to standard output in a way compatible with both, python2 and python3

问题描述

我想要一个函数，该函数返回一个文件对象，利用该对象可以将二进制数据写入标准输出.在python2中，sys.stdout是这样的对象.在python3中，它是sys.stdout.buffer.

I want a function returning a file object with which I can write binary data to standard output. In python2 sys.stdout is such an object. In python3 it is sys.stdout.buffer.

检索此类对象以使其同时适用于python2和python3解释器的最优雅/首选的方法是什么?

What is the most elegant/preferred way to retrieve such an object so that it works for both, the python2 and the python3 interpreter?

是检查sys.stdout.buffer是否存在的最佳方法(可能使用inspect模块)，如果存在，则将其返回，如果不存在，则假定我们在python2上并返回sys.stdout? >

Is the best way to check for existance of sys.stdout.buffer (probably using the inspect module) and if it exists, return it and if it doesnt, assume we are on python2 and return sys.stdout instead?

推荐答案

无需测试，只需使用 getattr() :

No need to test, just use getattr():

# retrieve stdout as a binary file object
output = getattr(sys.stdout, 'buffer', sys.stdout)

这会检索sys.stdout上的.buffer属性，但是如果该属性不存在(Python 2)，它将返回sys.stdout对象本身.

This retrieves the .buffer attribute on sys.stdout, but if it doesn't exist (Python 2) it'll return the sys.stdout object itself instead.

Python 2:

>>> import sys
>>> getattr(sys.stdout, 'buffer', sys.stdout)
<open file '<stdout>', mode 'w' at 0x100254150>

Python 3:

>>> import sys
>>> getattr(sys.stdout, 'buffer', sys.stdout)
<_io.BufferedWriter name='<stdout>'>

请注意，在Python 2中，stdout仍以文本模式打开，编写时换行符仍会转换为os.linesep. Python 3 BufferedWriter对象不会为您完成此操作.

Take into account that in Python 2, stdout is still opened in text mode, newlines are still translated to os.linesep when writing. The Python 3 BufferedWriter object won't do this for you.

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