observable alternatives and similar shards
Based on the "Misc" category.
Alternatively, view observable alternatives based on common mentions on social networks and blogs.
Do you think we are missing an alternative of observable or a related project?
Simple implementation of the Observer pattern in Crystal. It is loosely based on the Observable module from Ruby :)
The observer pattern is used to avoid tightly coupling objects that stand in a one-to-many relationship. It allows you to notify dependents about changes that happened to your object, without having hard-coded dependencies :)
Add to your shard.yml
dependencies: observable: github: tpei/observable branch: master
and then install the library into your project with
$ crystal deps
Include observable in the class you want to observe:
require "observable/observable" class ToObserve include Observable end
This provides you with the following methods:
add_observer(observer : Observer)
delete_observer(observer : Observer)
and as an added bonus, because I dislike the forced
changed call precondition:
notify_observers!, which notifies no matter if changed or not
Then you can include observer in the class you want observing:
require "observable/observer" class Observing include Observer def update(observable : Observable) # do whatever you want to do if your observable changes end end
This only gives you an
update(observable : Observable) method you should override, because it willl raise an error otherwise.
Unfortunately we don't have ruby's verbosity and dynamism here so it's all a little more static. Especially the
update method can really only pass on the