optional_depends GETTEXT \
		 --{enable,disable}-nls \
		 'for NLS support' &&
optional_depends CSHARP \
		 --{enable,disable}-csharp \
		 'for C# support' &&
optional_depends JAVA \
		 --{enable,disable}-java \
		 'for Java API support' &&
optional_depends gtk-doc \
		 --{enable,disable}-gtk-doc \
		 'use gtk-doc to build documentation'
