DESTDIR support and standard install variables

CHANGELOG.md

@@ -52,19 +52,20 @@ Release candidate for the next feature release, expected around 1 February 2025.
    / `solarsystem_hp()` type custom planet ephemeris provider functions currently configured, so they may be used
    directly, outside of `ephemeris()` calls.
 
- - #93: Now supporting `make install` with prefix support (e.g. `make prefix=/opt install` to install under `/opt`).
-   You can also set other standard directory variables, as prescribed in the 
+ - #93: Now supporting `make install` with prefix and DESTDIR support (e.g. `make prefix=/opt install` to install under 
+   `/opt`,  or `make DESTDIR="/tmp/stage" install` to stage install under `/tmp/stage`). You can also set other 
+   standard directory variables, as prescribed in the 
    [GNU standard](https://www.gnu.org/prep/standards/html_node/Directory-Variables.html) to further customize the
    install locations.
 
- - #95, #98: Added support for using orbital elements. `object.type` can now be set to `NOVAS_ORBITAL_OBJECT`, whose orbit
-   can be defined by the set of `novas_orbital_elements`, relative to a `novas_orbital_system`. You can initialize an 
-   `object` with a set of orbital elements using `make_orbital_object()`, and for planetary satellite orbits you might
-   use `novas_set_orbsys_pole()`. For orbital objects, `ephemeris()` will call on the new `novas_orbit_posvel()` to 
-   calculate positions. While orbital elements do not always yield precise positions, they can for shorter periods, 
-   provided that the orbital elements are up-to-date. For example, the Minor Planer Center (MPC) publishes accurate 
-   orbital elements for all known asteroids and comets regularly. For newly discovered objects, this may be the only 
-   and/or most accurate information available anywhere.
+ - #95, #98: Added support for using orbital elements. `object.type` can now be set to `NOVAS_ORBITAL_OBJECT`, whose 
+   orbit can be defined by the set of `novas_orbital_elements`, relative to a `novas_orbital_system`. You can 
+   initialize an `object` with a set of orbital elements using `make_orbital_object()`, and for planetary satellite 
+   orbits you might use `novas_set_orbsys_pole()`. For orbital objects, `ephemeris()` will call on the new 
+   `novas_orbit_posvel()` to calculate positions. While orbital elements do not always yield precise positions, they 
+   can for shorter periods, provided that the orbital elements are up-to-date. For example, the Minor Planer Center 
+   (MPC) publishes accurate orbital elements for all known asteroids and comets regularly. For newly discovered 
+   objects, this may be the only and/or most accurate information available anywhere.
 
  - #97: Added `NOVAS_EMB` (Earth-Moon Barycenter) and `NOVAS_PLUTO_BARYCENTER` to `enum novas_planets` to distinguish
    from the planet center in calculations.

Makefile

@@ -196,50 +196,54 @@ mydatadir ?= $(datadir)/supernovas
 docdir ?= $(datarootdir)/doc/supernovas
 htmldir ?= $(docdir)/html
 
+# Standard install commands
+INSTALL_PROGRAM ?= install
+INSTALL_DATA ?= install -m 644
+
 .PHONY: install
 install: install-libs install-cio-data install-headers install-apidoc install-examples
 
 .PHONY: install-libs
 install-libs:
 ifneq ($(wildcard $(LIB)/*),)
-	@echo "installing libraries to $(libdir)"
-	install -d $(libdir)
-	install -m 755 -D $(LIB)/lib*.so* $(libdir)/
+	@echo "installing libraries to $(DESTDIR)$(libdir)"
+	install -d $(DESTDIR)$(libdir)
+	$(INSTALL_PROGRAM) -D $(LIB)/lib*.so* $(DESTDIR)$(libdir)/
 else
 	@echo "WARNING! Skipping libs install: needs 'shared' and/or 'static'"
 endif
 
 .PHONY: install-cio-data
 install-cio-data:
-	@echo "installing CIO locator data to $(mydatadir)"
-	install -d $(mydatadir)
-	install -m 644 data/CIO_RA.TXT $(mydatadir)/CIO_RA.TXT
+	@echo "installing CIO locator data to $(DESTDIR)$(mydatadir)"
+	install -d $(DESTDIR)$(mydatadir)
+	$(INSTALL_DATA) data/CIO_RA.TXT $(DESTDIR)$(mydatadir)/CIO_RA.TXT
 
 .PHONY: install-headers
 install-headers:
-	@echo "installing headers to $(includedir)"
-	install -d $(includedir)
-	install -m 644 -D include/* $(includedir)/
+	@echo "installing headers to $(DESTDIR)$(includedir)"
+	install -d $(DESTDIR)$(includedir)
+	$(INSTALL_DATA) -D include/* $(DESTDIR)$(includedir)/
 
 .PHONY: install-apidoc
 install-apidoc:
 ifneq ($(wildcard apidoc/html/search/*),)
-	@echo "installing API documentation to $(htmldir)"
-	install -d $(htmldir)/search
-	install -m 644 -D apidoc/html/search/* $(htmldir)/search/
-	install -m 644 -D apidoc/html/*.* $(htmldir)/
-	@echo "installing Doxygen tag file to $(docdir)"
-	install -d $(docdir)
-	install -m 644 apidoc/supernovas.tag $(docdir)/supernovas.tag
+	@echo "installing API documentation to $(DESTDIR)$(htmldir)"
+	install -d $(DESTDIR)$(htmldir)/search
+	$(INSTALL_DATA) -D apidoc/html/search/* $(DESTDIR)$(htmldir)/search/
+	$(INSTALL_DATA) -D apidoc/html/*.* $(DESTDIR)$(htmldir)/
+	@echo "installing Doxygen tag file to $(DESTDIR)$(docdir)"
+	install -d $(DESTDIR)$(docdir)
+	$(INSTALL_DATA) apidoc/supernovas.tag $(DESTDIR)$(docdir)/supernovas.tag
 else
 	@echo "WARNING! Skipping apidoc install: needs doxygen and 'local-dox'"
 endif
 
 .PHONY: install-examples
 install-examples:
-	@echo "installing examples to $(docdir)"
-	install -d $(docdir)
-	install -m 644 -D examples/* $(docdir)
+	@echo "installing examples to $(DESTDIR)$(docdir)"
+	install -d $(DESTDIR)$(docdir)
+	$(INSTALL_DATA) -D examples/* $(DESTDIR)$(docdir)
 
 
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