Configuring a package

Many packages come with an autoconf-generated ./configure script for checking the build environment and configuring optional support for libraries. The econf function should be used where possible — this will provide correct build and path specifications for a Gentoo environment.

Often the configure script will try to automatically enable support for optional components based upon installed packages. This must not be allowed to happen. For example, if a user has Perl installed but has USE="-perl", packages with optional Perl support must not link against Perl. This automatic detection can usually be overridden using --enable- and --disable or --with- and --without- switches (but note that these don't always work — make sure these are tested properly!).

The use_enable and use_with utility functions should, where appropriate, be used to generate these switches.

src_configure() {
	# We have optional perl, python and ruby support
	econf \
		$(use_enable perl) \
		$(use_enable python) \
		$(use_enable ruby)
}

src_configure() {
	# Our package optional IPv6 support which uses --with rather than
	# --enable / --disable

	econf $(use_with ipv6)
}

Sometimes the package's choice of name for the option will not exactly match the name or case of the USE flag. This is very often the case with the X flag. For these situations, there are two argument forms:

src_configure() {
	# Our package has optional perl, python and ruby support
	econf \
		$(use_enable perl perlinterp) \
		$(use_enable python pythoninterp) \
		$(use_enable ruby rubyinterp)

	# ...
}

src_configure() {
	econf $(use_with X x11)
}

To check for an unset USE flag, the use_enable !flag form can be used.