title: How can I install the Python library 'gevent' on Mac OS X Lion
body: <p>Python library <code>gevent</code>, version 0.13.6 (the current version on PyPI) will not <code>pip install</code> on OS X Lion, Python 2.7 (and probably others.) It works fine on Snow Leopard.</p>
  
  <p>How can I get this library installed?</p>
  
  <p>Bonus points if it can be done using <code>pip install</code>, rather than a manual or custom process, because then it will play nicely with automated builds.</p>
  
  <p>Here is my <code>pip install</code> output:</p>
  
  <pre><code>pip install gevent
  Downloading/unpacking gevent
    Running setup.py egg_info for package gevent
  
  Requirement already satisfied (use --upgrade to upgrade): greenlet in ./tl_env/lib/python2.7/site-packages (from gevent)
  Installing collected packages: gevent
    Running setup.py install for gevent
      building 'gevent.core' extension
      gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -isysroot /Developer/SDKs/MacOSX10.6.sdk -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c gevent/core.c -o build/temp.macosx-10.6-intel-2.7/gevent/core.o
      In file included from gevent/core.c:225:
      gevent/libevent.h:9:19: error: event.h: No such file or directory
      gevent/libevent.h:38:20: error: evhttp.h: No such file or directory
      gevent/libevent.h:39:19: error: evdns.h: No such file or directory
      gevent/core.c:361: error: field ‘ev’ has incomplete type
      gevent/core.c:741: warning: parameter names (without types) in function declaration
      gevent/core.c: In function ‘__pyx_f_6gevent_4core___event_handler’:
      gevent/core.c:1619: error: ‘EV_READ’ undeclared (first use in this function)
      gevent/core.c:1619: error: (Each undeclared identifier is reported only once
      gevent/core.c:15376: warning: assignment makes pointer from integer without a cast
     [... about 1000 more lines of compiler errors...]
      gevent/core.c:15385: error: dereferencing pointer to incomplete type
      gevent/core.c: In function ‘__pyx_pf_6gevent_4core_4http___init__’:
      gevent/core.c:15559: warning: assignment makes pointer from integer without a cast
      gevent/core.c: At top level:
      gevent/core.c:21272: error: expected ‘)’ before ‘val’
      lipo: can't figure out the architecture type of: /var/folders/s5/t94kn0p10hdgxzx9_9sprpg40000gq/T//cczk54q7.out
      error: command 'gcc-4.2' failed with exit status 1
      Complete output from command /Users/jacob/code/toplevel/tl_env/bin/python -c "import setuptools;__file__='/Users/jacob/code/toplevel/tl_env/build/gevent/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --single-version-externally-managed --record /var/folders/s5/t94kn0p10hdgxzx9_9sprpg40000gq/T/pip-s2hPd3-record/install-record.txt --install-headers /Users/jacob/code/toplevel/tl_env/bin/../include/site/python2.7:
      running install
  
  running build
  
  running build_py
  
  running build_ext
  
  building 'gevent.core' extension
  
  gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -isysroot /Developer/SDKs/MacOSX10.6.sdk -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c gevent/core.c -o build/temp.macosx-10.6-intel-2.7/gevent/core.o
  </code></pre>