[GRASS-dev] GRASS 6.3.0

Glynn Clements glynn at gclements.plus.com
Fri Mar 21 02:29:08 EDT 2008

Markus Neteler wrote:

> I found that
> gui/wxpython/vdigit/
> fails on
> make -j4
> Something needs to be serialized there.

Fixed in SVN:

	-default: $(SHLIB) install_vdigit
	+default: install_vdigit
	+install_vdigit: $(SHLIB)
	 	$(INSTALL_DATA) _grass6_wxvdigit.so $(ETCDIR)/vdigit/
	 	$(INSTALL_DATA) grass6_wxvdigit.py $(ETCDIR)/vdigit/

Note to anyone writing Makefiles: a dependency line such as:

	target: source1 source2

states that source1 and source2 must be built before running the
commands for the rule. It does not require that source1 and source2
are built in that order. Although that will typically be the case for
a single-threaded build, a parallel build will attempt to build
source1 and source2 concurrently.

If source1 needs to be built before source2, this must be expressed through
dependencies, e.g.:

	target: source2

	source2: source1

Another problem with vdigit: the C++ wrapper file grass6_wxvdigit_wrap.cpp
is *not* a source file (it is built from the .i files using SWIG), and
should not be stored in the SVN repository. It should be generated by SWIG
during the build process.

However, this also lacks correct dependency information. First,
grass6_wxvdigit.i doesn't list the various .i files as dependencies,
so it won't be re-built if one of them is modified. Secondly, the rule
which generates grass6_wxvdigit_wrap.cpp doesn't actually have that
file as a target, so it won't get run if the file needs to be

Finally, while writing this, I've just noticed that gui/wxpython/Makefile

	default: install_scripts parsubdirs

which will run both targets concurrently. This is theoretically
problematic, as vdigit/Makefile assumes that the etc/wxpython/vdigit
directory has already been created. In practice, you'll get away with it,
as the chances of compiling the entire vdigit module before a mkdir
command has completed are essentially nil.

However, to avoid setting a bad example which may cause actual problems if
someone follows it, I've changed the rule to:

	default: install_scripts
		$(MAKE) parsubdirs

Note that parsubdirs is a "phony" target, so the following *won't* work:

	default: parsubdirs

	parsubdirs: install_scripts

Okay, I was wrong about the "finally" above; I've also changed:

	-	$(INSTALL_DATA) _grass6_wxvdigit.so $(ETCDIR)/vdigit/
	+	$(INSTALL_DATA) $(SHLIB) $(ETCDIR)/vdigit/

as the suffix won't be ".so" on all platforms.

Glynn Clements <glynn at gclements.plus.com>

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