cmake world: allow to build python bindings

cmake/OpenCVModule.cmake

@@ -233,7 +233,7 @@ macro(ocv_add_module _name)
 endmacro()
 
 # excludes module from current configuration
-macro(ocv_module_disable module)
+macro(ocv_module_disable_ module)
   set(__modname ${module})
   if(NOT __modname MATCHES "^opencv_")
     set(__modname opencv_${module})
@@ -246,9 +246,12 @@ macro(ocv_module_disable module)
     # touch variable controlling build of the module to suppress "unused variable" CMake warning
   endif()
   unset(__modname)
-  return() # leave the current folder
 endmacro()
 
+macro(ocv_module_disable module)
+  ocv_module_disable_(${module})
+  return() # leave the current folder
+endmacro()
 
 # collect modules from specified directories
 # NB: must be called only once!

modules/python/CMakeLists.txt

@@ -2,16 +2,26 @@
 #  CMake file for python support
 # ----------------------------------------------------------------------------
 
-if((WIN32 AND CMAKE_BUILD_TYPE STREQUAL "Debug")
-    OR BUILD_opencv_world
-    )
-  ocv_module_disable(python2)
-  ocv_module_disable(python3)
+if(ANDROID OR APPLE_FRAMEWORK OR WINRT)
+  set(__disable_python2 ON)
+  set(__disable_python3 ON)
+elseif(BUILD_opencv_world OR (WIN32 AND CMAKE_BUILD_TYPE STREQUAL "Debug"))
+  if(NOT DEFINED BUILD_opencv_python2)
+    set(__disable_python2 ON)
+  endif()
+  if(NOT DEFINED BUILD_opencv_python3)
+    set(__disable_python3 ON)
+  endif()
 endif()
 
-if(ANDROID OR APPLE_FRAMEWORK OR WINRT)
-  ocv_module_disable(python2)
-  ocv_module_disable(python3)
+if(__disable_python2)
+  ocv_module_disable_(python2)
+endif()
+if(__disable_python3)
+  ocv_module_disable_(python3)
+endif()
+if(__disable_python2 AND __disable_python3)
+  return()
 endif()
 
 add_subdirectory(python2)