Python:将子流程模块从 v3.3 导入到 v2.7.4

Question

我想将 subprocess 模块从 py v3.3 导入 v2.7 以便能够使用 timeout 功能。

在阅读了几篇文章后，我尝试了这个

from __future__ import subprocess

但是它说:

SyntaxError: future feature subprocess is not defined

然后我发现 future 没有任何特性 subprocess。

那么我应该在哪里以及如何从 v3.3 导入 subprocess？

Answer 1

我认为向后移植是个好主意。下面是 subprocess.call 的比较。请注意，在 *popenargs 之后使用命名参数 timeout 是 Python2 中的语法错误，因此向后移植有一个解决方法。其他函数的超时参数的处理方式类似。如果您对超时的实际实现方式感兴趣，您应该查看 Popen 的 wait 方法。

Python2.7子进程

def call(*popenargs, **kwargs):
    """Run command with arguments.  Wait for command to complete, then
    return the returncode attribute.

    The arguments are the same as for the Popen constructor.  Example:

    retcode = call(["ls", "-l"])
    """
    return Popen(*popenargs, **kwargs).wait()

Python3.3子进程

def call(*popenargs, timeout=None, **kwargs):
    """Run command with arguments.  Wait for command to complete or
    timeout, then return the returncode attribute.

    The arguments are the same as for the Popen constructor.  Example:

    retcode = call(["ls", "-l"])
    """
    with Popen(*popenargs, **kwargs) as p:
        try:
            return p.wait(timeout=timeout)
        except:
            p.kill()
            p.wait()
            raise

Python2.7 subprocess32 向后移植

def call(*popenargs, **kwargs):
    """Run command with arguments.  Wait for command to complete or
    timeout, then return the returncode attribute.

    The arguments are the same as for the Popen constructor.  Example:

    retcode = call(["ls", "-l"])
    """
    timeout = kwargs.pop('timeout', None)
    p = Popen(*popenargs, **kwargs)
    try:
        return p.wait(timeout=timeout)
    except TimeoutExpired:
        p.kill()
        p.wait()
        raise