Use python3 when available

src/algorithms/libs/volk_gnsssdr_module/volk_gnsssdr/cmake/Modules/VolkPython.cmake

@@ -25,42 +25,22 @@ set(__INCLUDED_VOLK_PYTHON_CMAKE TRUE)
 # This allows the user to specify a specific interpreter,
 # or finds the interpreter via the built-in cmake module.
 ########################################################################
-#this allows the user to override PYTHON_EXECUTABLE
-if(PYTHON_EXECUTABLE)
+set(VOLK_PYTHON_MIN_VERSION "2.7")
+set(VOLK_PYTHON3_MIN_VERSION "3.4")
+if (PYTHON_EXECUTABLE)
+    message(STATUS "User set python executable ${PYTHON_EXECUTABLE}")
+    find_package(PythonInterp ${VOLK_PYTHON_MIN_VERSION} REQUIRED)
+else (PYTHON_EXECUTABLE)
+    message(STATUS "PYTHON_EXECUTABLE not set - using default python3")
+    message(STATUS "Use -DPYTHON_EXECUTABLE=/path/to/python2 to build for python2.")
+    find_package(PythonInterp ${VOLK_PYTHON3_MIN_VERSION} REQUIRED)
+endif (PYTHON_EXECUTABLE)
 
-    set(PYTHONINTERP_FOUND TRUE)
+if (${PYTHON_VERSION_MAJOR} VERSION_EQUAL 3)
+    set(PYTHON3 TRUE)
+endif ()
 
-#otherwise if not set, try to automatically find it
-else(PYTHON_EXECUTABLE)
-
-    #use the built-in find script
-    set(Python_ADDITIONAL_VERSIONS 3.4 3.5 3.6)
-    find_package(PythonInterp 2)
-
-    #and if that fails use the find program routine
-    if(NOT PYTHONINTERP_FOUND)
-        find_program(PYTHON_EXECUTABLE NAMES python python2 python2.7 python3)
-        if(PYTHON_EXECUTABLE)
-            set(PYTHONINTERP_FOUND TRUE)
-        endif(PYTHON_EXECUTABLE)
-    endif(NOT PYTHONINTERP_FOUND)
-
-endif(PYTHON_EXECUTABLE)
-
-#make the path to the executable appear in the cmake gui
-set(PYTHON_EXECUTABLE ${PYTHON_EXECUTABLE} CACHE FILEPATH "python interpreter")
-
-#make sure we can use -B with python (introduced in 2.6)
-if(PYTHON_EXECUTABLE)
-    execute_process(
-        COMMAND ${PYTHON_EXECUTABLE} -B -c ""
-        OUTPUT_QUIET ERROR_QUIET
-        RESULT_VARIABLE PYTHON_HAS_DASH_B_RESULT
-    )
-    if(PYTHON_HAS_DASH_B_RESULT EQUAL 0)
-        set(PYTHON_DASH_B "-B")
-    endif()
-endif(PYTHON_EXECUTABLE)
+find_package(PythonLibs ${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR} EXACT)
 
 ########################################################################
 # Check for the existence of a python module:
@@ -69,28 +49,32 @@ endif(PYTHON_EXECUTABLE)
 # - cmd an additional command to run
 # - have the result variable to set
 ########################################################################
-macro(VOLK_PYTHON_CHECK_MODULE desc mod cmd have)
-    message(STATUS "")
-    message(STATUS "Python checking for ${desc}")
+macro(VOLK_PYTHON_CHECK_MODULE_RAW desc python_code have)
     execute_process(
-        COMMAND ${PYTHON_EXECUTABLE} -c "
-#########################################
-try: import ${mod}
-except:
-    try: ${mod}
-    except: exit(-1)
-try: assert ${cmd}
-except: exit(-1)
-#########################################"
-        RESULT_VARIABLE ${have}
+        COMMAND ${PYTHON_EXECUTABLE} -c "${python_code}"
+        OUTPUT_QUIET ERROR_QUIET
+        RESULT_VARIABLE return_code
     )
-    if(${have} EQUAL 0)
+    if(return_code EQUAL 0)
         message(STATUS "Python checking for ${desc} - found")
         set(${have} TRUE)
-    else(${have} EQUAL 0)
+    else()
         message(STATUS "Python checking for ${desc} - not found")
         set(${have} FALSE)
-    endif(${have} EQUAL 0)
+    endif()
+endmacro(VOLK_PYTHON_CHECK_MODULE_RAW)
+
+macro(VOLK_PYTHON_CHECK_MODULE desc mod cmd have)
+    VOLK_PYTHON_CHECK_MODULE_RAW(
+        "${desc}" "
+#########################################
+try:
+    import ${mod}
+    assert ${cmd}
+except (ImportError, AssertionError): exit(-1)
+except: pass
+#########################################"
+    "${have}")
 endmacro(VOLK_PYTHON_CHECK_MODULE)
 
 ########################################################################
@@ -98,8 +82,12 @@ endmacro(VOLK_PYTHON_CHECK_MODULE)
 ########################################################################
 if(NOT DEFINED VOLK_PYTHON_DIR)
 execute_process(COMMAND ${PYTHON_EXECUTABLE} -c "
-from distutils import sysconfig
-print(sysconfig.get_python_lib(plat_specific=True, prefix=''))
+import os
+import sys
+if os.name == 'posix':
+    print(os.path.join('lib', 'python' + sys.version[:3], 'dist-packages'))
+if os.name == 'nt':
+    print(os.path.join('Lib', 'site-packages'))
 " OUTPUT_VARIABLE VOLK_PYTHON_DIR OUTPUT_STRIP_TRAILING_WHITESPACE
 )
 endif()