为Scrapy安装包依赖项

Question

在使用Scrapy时，用户需要安装很多软件包，我觉得我在安装pyOpenSSL时遇到了问题。

当我尝试创建一个教程中的Scrapy项目时，出现了以下输出：

Traceback (most recent call last):
  File "C:\Python27\lib\runpy.py", line 162, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "C:\Python27\lib\runpy.py", line 72, in _run_code
    exec code in run_globals
  File "C:\Python27\lib\site-packages\scrapy\cmdline.py", line 168, in <module>
    execute()
  File "C:\Python27\lib\site-packages\scrapy\cmdline.py", line 122, in execute
    cmds = _get_commands_dict(settings, inproject)
  File "C:\Python27\lib\site-packages\scrapy\cmdline.py", line 46, in _get_comma
nds_dict
    cmds = _get_commands_from_module('scrapy.commands', inproject)
  File "C:\Python27\lib\site-packages\scrapy\cmdline.py", line 29, in _get_comma
nds_from_module
    for cmd in _iter_command_classes(module):
  File "C:\Python27\lib\site-packages\scrapy\cmdline.py", line 20, in _iter_comm
and_classes
    for module in walk_modules(module_name):
  File "C:\Python27\lib\site-packages\scrapy\utils\misc.py", line 68, in walk_mo
dules
    submod = import_module(fullpath)
  File "C:\Python27\lib\importlib\__init__.py", line 37, in import_module
    __import__(name)
  File "C:\Python27\lib\site-packages\scrapy\commands\bench.py", line 3, in <mod
ule>
    from scrapy.tests.mockserver import MockServer
  File "C:\Python27\lib\site-packages\scrapy\tests\mockserver.py", line 6, in <m
odule>
    from twisted.internet import reactor, defer, ssl
  File "C:\Python27\lib\site-packages\twisted\internet\ssl.py", line 59, in <mod
ule>
    from OpenSSL import SSL
  File "build\bdist.win32\egg\OpenSSL\__init__.py", line 8, in <module>
  File "build\bdist.win32\egg\OpenSSL\rand.py", line 11, in <module>
  File "build\bdist.win32\egg\OpenSSL\_util.py", line 3, in <module>
ImportError: No module named cryptography.hazmat.bindings.openssl.binding

然后我在网上搜索了最后一个错误（没有名为cryptography.hazmat的模块），发现有几处提到pyOpenSSL。所以我决定运行 easy_install pyOpenSSL==0.14 来确保安装的是最新版本，但执行后却得到了这个输出：

c:\python27\include\pymath.h(22) : warning C4273: 'round' : inconsistent dll lin
kage
        C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\math.h(51
6) : see previous definition of 'round'
c:\users\bk\appdata\local\temp\easy_install-tztawu\cryptography-0.4\temp\easy_in
stall-svxsjy\cffi-0.8.2\c\misc_win32.h(225) : error C2632: 'char' followed by 'b
ool' is illegal
c:\users\bk\appdata\local\temp\easy_install-tztawu\cryptography-0.4\temp\easy_in
stall-svxsjy\cffi-0.8.2\c\misc_win32.h(225) : warning C4091: 'typedef ' : ignore
d on left of 'unsigned char' when no variable is declared
c/_cffi_backend.c(5295) : warning C4146: unary minus operator applied to unsigne
d type, result still unsigned
c/_cffi_backend.c(5296) : warning C4146: unary minus operator applied to unsigne
d type, result still unsigned
c/_cffi_backend.c(5297) : warning C4146: unary minus operator applied to unsigne
d type, result still unsigned
c/_cffi_backend.c(5298) : warning C4146: unary minus operator applied to unsigne
d type, result still unsigned
error: Setup script exited with error: command '"C:\Program Files (x86)\Microsof
t Visual Studio 12.0\VC\BIN\cl.exe"' failed with exit status 2

所以我有点迷茫，不知道该怎么做才能让Scrapy正常运行。

软件包管理错误排查 pyopenssl cryptography scrapy 依赖项

为Scrapy安装包依赖项

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