Look for Python using find_package()

[moubctez]

In CMake, Python should be detected with find_package() (not FIND_PROGRAM). If there multiple Python versions installed (in my case, there is a system Python and various versions from PkgSrc), it might not be the version we want.

Here's my patch to deal with the issue:

--- apps/CMakeLists.txt.orig	2022-02-22 20:49:04.000000000 +0000
+++ apps/CMakeLists.txt
@@ -21,8 +21,8 @@ ENDIF(INSTALL_HELPER_SCRIPTS)
 
 # Inspired by http://bloerg.net/2012/11/10/cmake-and-distutils.html
 
-FIND_PROGRAM(PYTHON "python3")
-IF(PYTHON)
+find_package (Python3 COMPONENTS Interpreter)
+IF(Python3_FOUND)
     SET(SETUP_PY_IN "${CMAKE_CURRENT_SOURCE_DIR}/setup.py.in")
     SET(SETUP_PY    "${CMAKE_CURRENT_BINARY_DIR}/setup.py")
     SET(DEPS_IN     "${CMAKE_CURRENT_SOURCE_DIR}/lensfun/__init__.py.in")
@@ -33,7 +33,7 @@ IF(PYTHON)
     CONFIGURE_FILE(${DEPS_IN} ${DEPS})
 
     ADD_CUSTOM_COMMAND(OUTPUT ${OUTPUT}
-                       COMMAND ${PYTHON} ${SETUP_PY} build
+                       COMMAND ${Python3_EXECUTABLE} ${SETUP_PY} build
                        COMMAND ${CMAKE_COMMAND} -E touch ${OUTPUT}
                        DEPENDS ${DEPS_IN})
 
@@ -42,5 +42,5 @@ IF(PYTHON)
     IF(NOT DEFINED SETUP_PY_INSTALL_PREFIX)
       SET(SETUP_PY_INSTALL_PREFIX "${CMAKE_INSTALL_PREFIX}")
     ENDIF()
-    INSTALL(CODE "execute_process(COMMAND ${PYTHON} ${SETUP_PY} install --prefix=\$ENV{DESTDIR}${SETUP_PY_INSTALL_PREFIX})")
+    INSTALL(CODE "execute_process(COMMAND ${Python3_EXECUTABLE} ${SETUP_PY} install --root=\$ENV{DESTDIR})")
 ENDIF(PYTHON)

[payano]

Hello, Could you please do a PR instead?