title: Cmake could not find boost_python
body: <p>I am trying to build this simple boost python demo from <a href="https://gist.github.com/ndevenish/ff771feb6817f7debfa728386110f567" rel="noreferrer">this link</a> on my MacOS High Sierra.</p>
  
  <p>Following is the <code>hello_ext.cpp</code>:</p>
  
  <pre><code>#include &lt;boost/python.hpp&gt;
  
  char const* greet()
  {
    return "hello, world";
  }
  
  BOOST_PYTHON_MODULE(hello_ext)
  {
    using namespace boost::python;
    def("greet", greet);
  }
  </code></pre>
  
  <p>Following is the <code>CmakeLists.txt</code>:</p>
  
  <pre><code>cmake_minimum_required(VERSION 3.5)
  
  # Find python and Boost - both are required dependencies
  find_package(PythonLibs 2.7 REQUIRED)
  find_package(Boost COMPONENTS python REQUIRED)
  
  # Without this, any build libraries automatically have names "lib{x}.so"
  set(CMAKE_SHARED_MODULE_PREFIX "")
  
  # Add a shared module - modules are intended to be imported at runtime.
  # - This is where you add the source files
  add_library(hello_ext MODULE hello_ext.cpp)
  
  # Set up the libraries and header search paths for this target
  target_link_libraries(hello_ext ${Boost_LIBRARIES} ${PYTHON_LIBRARIES})
  target_include_directories(hello_ext PRIVATE ${PYTHON_INCLUDE_DIRS})
  </code></pre>
  
  <p>I figured I need to install python. Boost 1.69 was already installed and I did <code>brew install boost-python</code> which worked fine. Doing a <code>brew list | grep 'boost'</code> lists out <code>boost</code> and <code>boost-python</code>. </p>
  
  <p>But, doing a <code>cmake ..</code> from a <code>build</code> directory complains the following:</p>
  
  <pre><code>Could not find the following Boost libraries:
  
        boost_python
  
  No Boost libraries were found.  You may need to set BOOST_LIBRARYDIR to 
  the directory containing Boost libraries or BOOST_ROOT to the location 
  of Boost.
  </code></pre>
  
  <p>What am I missing here?</p>