Writing Makefiles

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Some tips for writing clean Makefile.am's in Apertium:

Use apertium-init[edit]

If you're creating a new monolingual module or pair, use apertium-init. It creates modules that Just Work. If you've got a problem with an old makefile, throw it all away and create a new one using apertium-init.


If you really want to debug your old makefile, read on for some tips.

Modes[edit]

If you have apertium version 3.3 or higher, you can do this to simplify dealing with Modes files / modes.xml:

In configure.ac, add this:

AP_MKINCLUDE

In Makefile.am, add this:

# Only include one mode file here, the rest will be built along with it (listing several leads to problems with parallell make):
noinst_DATA=modes/$(PREFIX1).mode

@ap_include@

# Most language pairs don't need to specify anything else for install-data-local:
install-data-local: install-modes

EXTRA_DIST: 
	modes.xml \
	# here you'll typically also have other things, like .dix and .t1x 
        # files that are to be included when you make a release

Nowhere else should modes be mentioned in the Makefile.am.

If you follow this system, the modes with install="yes" in modes.xml will be installed, and you won't end up with root-owned modes files, and make -j4 will work fine.

Use .deps/.d to say that the .deps directory must be created[edit]

Say you have several goals that put temporary files in .deps/, e.g.

.deps/apertium-wat-lol.lol.dix: apertium-wat-lol.lol.dix
	test -d .deps || mkdir .deps
	xsltproc lexchoicebil.xsl $< >$@

and so on. The .deps directory has to be created for the file in .deps to be created. If you put mkdir .deps in each such goal, you can get a race condition where two goals try to make .deps at the same time.

The solution is this: if a goal needs the .deps directory to be created, let it depend on the file .deps/.d. First put this in Makefile.am:

.deps/.d:
	test -d .deps || mkdir .deps
	touch $@

.PRECIOUS: .deps/.d

(If using apertium 3.3 or higher, you can just do AP_MKINCLUDE, which includes the above .deps/.d goal.)

And then, instead of creating the dir in each goal, just depend on .deps/.d for those goals:

.deps/apertium-wat-lol.lol.dix: apertium-wat-lol.lol.dix .deps/.d
	xsltproc lexchoicebil.xsl $< >$@

(The PRECIOUS line prevents the .d file from being cleaned up and removed automatically.)

Removing directories on make clean[edit]

Say you want to remove .deps and modes on "make clean". Don't do CLEANFILES=-rf .deps modes file1 file2 …, it doesn't work everywhere.

A more portable solution is this:

CLEANFILES = $(TARGETS_COMMON)
clean-local: 
	-rm -rf .deps modes

Where does this $AP_SRC1 stuff come from?[edit]

When you do ./autogen.sh --with-lang1=foo, the variable AP_SRC1 will be set to "foo" in the Makefile. Your configure.ac should say something like AP_CHECK_LING([1], [apertium-lol]) for that option to work.


The details
The autogen.sh script passes its arguments on to the configure script. If configure.ac says e.g. AP_CHECK_LING([1], [apertium-lol]), then the configure script will have a --with-lang1 option to set to the location of the package apertium-lol. If you don't pass --with-lang1 to autogen.sh, configure will attempt to find the location of an installed apertium-lol package using pkg-config.
The gory details
The actual configure code for all this checking is in apertium.m4, typically in /usr/share/aclocal/apertium.m4 or /usr/local/share/aclocal/apertium.m4 if you're very interested in reading m4sh code.