1# Copyright 2017 Rene Rivera 2# Distributed under the Boost Software License, Version 1.0. 3# (See accompanying file LICENSE_1_0.txt or copy at 4# http://www.boost.org/LICENSE_1_0.txt) 5 6import feature ; 7 8#| tag::doc[] 9 10[[bbv2.builtin.features.conditional]]`conditional`:: 11Used to introduce indirect conditional requirements. The value should have the 12form: 13+ 14---- 15@rulename 16---- 17+ 18where _rulename_ should be a name of a rule with the following signature: 19+ 20---- 21rule rulename ( properties * ) 22---- 23+ 24The rule will be called for each target with its properties and should return 25any additional properties. See also section <<Requirements>> for an example. 26 27|# # end::doc[] 28 29feature.feature conditional 30 : 31 : incidental free ; 32