build(meson): more robust python build

meson.build

@@ -18,11 +18,32 @@
 #   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 #
 # *********************************************************************** #
-project('libconstants', 'cpp', version: 'v1.1.5', default_options: ['cpp_std=c++23'], meson_version: '>=1.5.0')
+project('libconstants', 'cpp', version: 'v1.1.6', default_options: ['cpp_std=c++23'], meson_version: '>=1.5.0')
 
 # Add default visibility for all C++ targets
 add_project_arguments('-fvisibility=default', language: 'cpp')
 
+if get_option('build_python')
+    local_py_install = import('python').find_installation('python3', pure: false)
+    fourdst_pkg = local_py_install.get_install_dir() / 'fourdst'
+
+    constants_libdir             = fourdst_pkg / 'lib'
+    constants_header_install_dir = fourdst_pkg / 'include' / 'fourdst' / 'constants'
+
+    vendor_lib_dir             = fourdst_pkg / 'lib' / 'vendor'
+    vendor_header_dir          = fourdst_pkg / 'include' / 'fourdst' / 'vendor'
+
+    message('Installing libconfig in python mode. Install locations are...')
+else
+    constants_libdir             = get_option('libdir')
+    constants_header_install_dir = get_option('includedir') / 'fourdst' / 'constants'
+
+    message('Installing libconfig in non python (normal) mode. Install locations are...')
+endif
+message('    Libraries: ' + constants_libdir)
+message('    Headers:   ' + constants_header_install_dir)
+
+
 cpp = meson.get_compiler('cpp')
 
 subdir('assets/static')
@@ -45,7 +66,6 @@ if get_option('pkg_config')
         description: 'Physical Constants for SERiF and related projects',
         version: meson.project_version(),
         libraries: [libconst, '-Wl,-rpath,${libdir}'],
-        subdirs: ['fourdst'],
         filebase: 'fourdst_constants',
         install_dir: join_paths(get_option('libdir'), 'pkgconfig')
     )