# RoleMixin.java

    /*
     * Copyright 2011 Marc Grue.
     *
     * Licensed  under the  Apache License,  Version 2.0  (the "License");
     * you may not use  this file  except in  compliance with the License.
     * You may obtain a copy of the License at
     *
     *   http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed  under the  License is distributed on an "AS IS" BASIS,
     * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
     * implied.
     *
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.qi4j.sample.dcicargo.sample_b.infrastructure.dci;

    import org.qi4j.api.injection.scope.Structure;
    import org.qi4j.api.query.QueryBuilderFactory;
    import org.qi4j.api.unitofwork.UnitOfWorkFactory;
    import org.qi4j.api.value.ValueBuilderFactory;

    /**
     * RoleMixin
     *
     * Base class for Methodful Roles in Contexts
     *
     * Helps "inject" the Context object into the Role Player.
     *
     * The context field name is now "c" since we don't want the word "context" interfere
     * with domain semantics. We could for instance in one domain have some "material context"
     * where "context" is not a DCI Context but the context of some material. In that case a
     * DCI keyword "context" would confuse the semantics. We could also use "ctx", but why not
     * the shortest option? Less typing, and we know what it is. Furthermore a single letter is
     * easier to spot in the code masses than "ctx" (good to be able to quickly spot all uses
     * of the Context).
     */
    public abstract class RoleMixin<T extends Context>
    {
        // Context object reference
        public T c;

        // Other common role services/methods could be added here...

        @Structure
        public UnitOfWorkFactory uowf;

        @Structure
        public QueryBuilderFactory qbf;

        @Structure
        public ValueBuilderFactory vbf;

        /**
         * setContext is called with method invocation in {@link Context#setContext(Object, Context)}
         * (therefore "never used" according to IDE)
         */
        public void setContext( T context )
        {
            c = context;
        }
    }