i have never heard about query-writer before (this discussions happened at a time before i looked in openacs), but found some forum-posts about it. it seems to me as an interceptor for the life-cycle and accessor functions of acs-objects on the database layer. Is this right?
Using powerful language constructs can be very constructive or very distructive. Some languages are designed to limit the harm, a bad progammer can do. Some other languages are designed for empowering the power-users. xotcl was certainly designed for the seconds category, where a good design can be achieved with a few statments (the initial goal was to provide language constructs for design patterns, for adding and removing these dynamically). no language guarantees quality, quality control is needed always. It certainly makes no sense to use every language construct in every situation.
My point was not to talk about xotcl, but about product line architectures, about ways to manage variablility in code installations, which is a serious problem in complex real life situations.
