Improve python bindings Makefile

Makefile

@@ -21,8 +21,7 @@ makefiles = \
   misc/upstart/local.mk \
   doc/manual/local.mk \
   tests/local.mk \
-  tests/plugins/local.mk \
-  python/local.mk
+  tests/plugins/local.mk
 
 -include Makefile.config
 

python/Makefile

@@ -1,9 +1,49 @@
-build:
-	$(MAKE) -C .. python/build
-	meson compile -C build
+# This Makefile is only used for development of the Python bindings, it is not
+# used in the Nix build.
+# The reason this exists is to make it easier to develop the Python bindings in
+# tandem with the main Nix.
+# The default `make` (defaults to `make build`) calls the main Nix projects
+# `make install` before calling the Python bindings' `meson compile`, therefore
+# ensuring that the needed Nix dynamic libraries are up-to-date
 
-test:
-	$(MAKE) -C .. python/build
-	meson test -C build -v
+builddir=build
 
-.PHONY: build test
+.PHONY: build
+build: nix-install setup-done
+	meson compile -C $(builddir)
+
+.PHONY: test
+test: nix-install setup-done
+	meson test -C $(builddir) -v
+
+.PHONY: clean
+clean:
+	rm -rf $(builddir)
+
+# We include the main Nix projects Makefile.config file to know the $(libdir)
+# variable, which is where Nix is installed in, which we can then use to setup
+# the meson build
+include ../Makefile.config
+
+# We need the file to exist though
+../Makefile.config:
+	@# Throw a good error message in case ./configure hasn't been run yet
+	@[[ -e ../config.status ]] || ( echo "The main Nix project needs to be configured first, see https://nixos.org/manual/nix/stable/contributing/hacking.html" && exit 1 )
+	@# If ./configure is done, we can create the file ourselves
+	$(MAKE) -C .. Makefile.config
+
+.PHONY: setup
+setup: nix-install
+	@# Make meson be able to find the locally-installed Nix
+	PKG_CONFIG_PATH=$(libdir)/pkgconfig:$$PKG_CONFIG_PATH meson setup $(builddir)
+
+.PHONY: setup-done
+setup-done:
+	@# A better error message in case the build directory doesn't exist yet
+	@[[ -e $(builddir) ]] || ( echo "Run 'make setup' once to configure the project build directory" && exit 1 )
+
+.PHONY: nix-install
+nix-install:
+	@# The python bindings don't technically need an _entire_ Nix installation,
+	@# but it seems non-trivial to pick out only exactly the files it actually needs
+	$(MAKE) -C .. install