depends libxml2 && optional_depends perl --with-perl-binding --without-perl-binding "for perl bindings" && optional_depends python --with-python-binding --without-python-binding "for python bindings" && optional_depends g++ --with-cxx-binding --without-cxx-binding "for c++ bindings and demo" && optional_depends tcl --with-tcl-binding --without-tcl-binding "for tcl bindings and demo" && optional_depends gd --with-rigmatrix --without-rigmatrix "for the rigmatrix tool"