More than a few people have noticed the similarities between add-watch, and event/data binding in things like Backbone.js.
Maybe its worth considering if a feature marked as "alpha" is really the best thing for this case. 1. add-watch arguments are verbose. Do we really need a key to name the watcher, and the old value? For the vast majority of cases, no. 2. cascading changes is verbose. Often you want the watcher to update another atom, but all this needs to be set up manually. Perhaps something simpler like (echo f some-atom) could return a new atom, whose value is (f some-atom) and is updated with each change. 3. Incremental updates are difficult; the action performed on the source atom is opaque Simply being informed of values is not enough -- if you know what action was performed on the source atom, you can proceed more efficiently. Instead of recomputing an entire sequence of dom elements, you could insert/delete the relevant ones, or decide which other actions need to be taken. This last problem could potentially be addressed by adding meta-data to the update action, which is then propagated to the watchers. Another approach would be to introduce new reference types corresponding to clojure collections, atom-vector and atom-map, which could incrementally update themselves from the source atom. Something like (echo f (atom-vector X)), where atom-vector implements a protocol allowing for incremental updates which then get propagated to echo'ing atom. Figuring out a reasonable way to deal with collections is a big stumbling block for me, in trying to build data-binding abstractions in clojurescript. Recomputing everything is suboptimal (though it is also suboptimal that there is no data sharing in the current implementation of the clojurescript collections so you end up copying everything on each modification anyway) -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
