Problem with catkin_make in Arch_linux

edit

Hi

I followed the instructions in http://wiki.ros.org/indigo/Installation/Arch.

If i typed catkin_make i get

Exhibt A :

[neo@arch ros2]$ indigo
[neo@arch ros2]$ catkin_make
Base path: /home/neo/ros2
Source space: /home/neo/ros2/src
Build space: /home/neo/ros2/build
Devel space: /home/neo/ros2/devel
Install space: /home/neo/ros2/install
####
#### Running command: "cmake /home/neo/ros2/src -DCATKIN_DEVEL_PREFIX=/home/neo/ros2/devel -DCMAKE_INSTALL_PREFIX=/home/neo/ros2/install" in "/home/neo/ros2/build"
####
-- Using CATKIN_DEVEL_PREFIX: /home/neo/ros2/devel
-- Using CMAKE_PREFIX_PATH: /opt/ros/indigo
-- This workspace overlays: /opt/ros/indigo
-- Using PYTHON_EXECUTABLE: /usr/bin/python
-- Using default Python package layout
-- Could NOT find PY_em (missing:  PY_EM) 
CMake Error at /opt/ros/indigo/share/catkin/cmake/empy.cmake:29 (message):
  Unable to find either executable 'empy' or Python module 'em'...  try
  installing the package 'python-empy'
Call Stack (most recent call first):
  /opt/ros/indigo/share/catkin/cmake/all.cmake:146 (include)
  /opt/ros/indigo/share/catkin/cmake/catkinConfig.cmake:20 (include)
  CMakeLists.txt:52 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/neo/ros2/build/CMakeFiles/CMakeOutput.log".
Invoking "cmake" failed

But if i do the following catkin_make works

Exhibt B :

[neo@arch ros2]$ indigo
[neo@arch ros2]$ catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python2 -DPYTHON_INCLUDE_DIR=/usr/include/python2.7 -DPYTHON_LIBRARY=/usr/lib/libpython2.7.so
Base path: /home/neo/ros2
Source space: /home/neo/ros2/src
Build space: /home/neo/ros2/build
Devel space: /home/neo/ros2/devel
Install space: /home/neo/ros2/install
####
#### Running command: "cmake /home/neo/ros2/src -DCATKIN_DEVEL_PREFIX=/home/neo/ros2/devel -DCMAKE_INSTALL_PREFIX=/home/neo/ros2/install -DPYTHON_EXECUTABLE=/usr/bin/python2 -DPYTHON_INCLUDE_DIR=/usr/include/python2.7 -DPYTHON_LIBRARY=/usr/lib/libpython2.7.so" in "/home/neo/ros2/build"
####
-- Using CATKIN_DEVEL_PREFIX: /home/neo/ros2/devel
-- Using CMAKE_PREFIX_PATH: /opt/ros/indigo
-- This workspace overlays: /opt/ros/indigo
-- Found PythonInterp: /usr/bin/python2 (found version "2.7.8") 
-- Using PYTHON_EXECUTABLE: /usr/bin/python2
-- Using default Python package layout
-- Found PY_em: /usr/lib/python2.7/site-packages/em.pyc  
-- Using empy: /usr/lib/python2.7/site-packages/em.pyc
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /home/neo/ros2/build/test_results
-- Found gtest: gtests will be built
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.6.9
-- BUILD_SHARED_LIBS is on
-- Configuring done
-- Generating done
CMake Warning:
  Manually-specified variables were not used by the project:

    PYTHON_INCLUDE_DIR
    PYTHON_LIBRARY


-- Build files have been written to: /home/neo/ros2/build
####
#### Running command: "make -j4 -l4" in "/home/neo/ros2/build"
####

The problem is as i understand is because of the package empy. Also i see that in the log output of Exhibit A The PYTHON_EXECUTABLE: /usr/bin/python and not as PYTHON_EXECUTABLE: /usr/bin/python2 which is seen in Exhibit B.

How can this be ?