observer-pattern

Is it possible to add observer to tableView.contentOffset?

由 落爺英雄遲暮 提交于 2019-12-10 04:10:03
问题 I need to track tableView.contentOffset.y Is it possible to add observer to tableView.contentOffset? I think this is impossible because contentOffset doesn't inherit NSObject class. Is any other solution? 回答1: UITableView is a UIScrollView subclass so you can use the UIScrollViewDelegate method scrollViewDidScroll: to be notified when the view scrolled. Check the contentOffset of the scrollView in that method contentOffset is a key path, so you can also observe its changes using KVO [self

Design Pattern for multithreaded observers

由 落爺英雄遲暮 提交于 2019-12-09 23:13:09
问题 In a digital signal acquisition system, often data is pushed into an observer in the system by one thread. example from Wikipedia/Observer_pattern: foreach (IObserver observer in observers) observer.Update(message); When e.g. a user action from e.g. a GUI-thread requires the data to stop flowing, you want to break the subject-observer connection, and even dispose of the observer alltogether. One may argue: you should just stop the data source, and wait for a sentinel value to dispose of the

Observer Pattern in Swift

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-09 11:58:04
问题 I want to implement an observer pattern, but I do not find the proper programming language constructs in Swift (also 2.0). The main problems are: protocol and extension does not allow stored properties. In classes we could add stored properties, but we can not force a subclass to override some of its inherited methods. This is what I want: {class|protocol|extension|whathaveyou} Sensor { var observers = Array<Any>() // This is not possible in protocol and extensions // The following is does

Ember.js + JQuery-UI Tooltip - Tooltip does not reflect the model / controller changes

由 北城以北 提交于 2019-12-08 20:12:57
Context I have a small Ember app, which, amongst other things, displays a number of connected users and, when hovering an element of the page, their names as a list. All in all, it works quite well. The applications pulls data from a REST endpoint every two minutes, as the backend didn't allow for pushing data. The contents of the tooltip are computed in the Controller, with a function that basically concatenate strings in various ways according to the context. Then it's bound to a data attribute of the <img> the tooltip is created on. When the View is ready and didInsertElement is fired, the

Rxjs Subject next() after complete()

由 我的未来我决定 提交于 2019-12-08 19:08:36
问题 I have service which connects with Subject() to do paging. I'm using next(newData) to pass to subject, which keeps things alive, now I need to use complete() on each ajax call and pass it to subject. but after doing one complete() I'm started get error. I wanted to know, can we still pass Subject observables still next(newData) if once completed() is already been triggered? 回答1: There is some information on subjects from a former question on stack overflow : here. I encourage you to review it

How to suspend notification to observers while doing many changes using a ContentProvider

由 喜欢而已 提交于 2019-12-08 08:43:32
问题 I have an ExpandableListView that uses a SimpleCursorTreeAdapter which uses the cursors returned by a ContentProvider. This is fine as it always keeps in sync with the data but sometimes I need to do many changes to the database so that the cursor is requeried many times in the same second. Is it possible to suspend the notification of ContentObservers to avoid unnecessary requerys? 回答1: A possible solution is to modify the content provider to allow suspending notifications. URIs to be

RoR: undefined method `url_for' for nil:NilClass

由 北城以北 提交于 2019-12-08 08:24:54
问题 I have a standard Rails application. When a Tip is created, I would like to create a Message for each User who is interested in that Tip. This sounds simple right? It should be... So, we start with a Tip Observer: class TipObserver < ActiveRecord::Observer def after_save(tip) # after the tip is saved, we'll create some messages to inform the users users = User.interested_in(tip) # get the relevant users users.each do |u| m = Message.new m.recipient = u link_to_tip = tip_path(tip) m.body =

Ember.js + JQuery-UI Tooltip - Tooltip does not reflect the model / controller changes

由 爷，独闯天下 提交于 2019-12-08 03:30:47
问题 Context I have a small Ember app, which, amongst other things, displays a number of connected users and, when hovering an element of the page, their names as a list. All in all, it works quite well. The applications pulls data from a REST endpoint every two minutes, as the backend didn't allow for pushing data. The contents of the tooltip are computed in the Controller, with a function that basically concatenate strings in various ways according to the context. Then it's bound to a data

Logical pattern for listeners/observers to implement RecyclerView list and details activities

由 谁说我不能喝 提交于 2019-12-08 02:31:02
问题 There seems to be various ways to implement RecyclerView lists, some more logical than others. Going beyond a simple list to one where the data changes increases the complexity. Additional complexity comes from implementing the ability to view the details of the list items. Although I have had some success at implementing lists in this manner, I feel that what I've come-up with is not efficient and not what was intended when the framework was designed. Looking at the various methods I've used

Having trouble getting the observer pattern working

由 最后都变了- 提交于 2019-12-08 02:13:38
问题 I have been trying to no avail to get the observer pattern working in a relatively simple application. I have 4 GUI classes StarterClass (contains a CompositeWordLists and a CompositeWordListData ) CompositeWordLists (contains many CompositeListItem /s and a CompositeWordListData ) CompositeListItem CompositeWordListData (Contains a DialogWordData ) DialogWordData Here is my Observable interface Observable<T> { void addObserver(T o); void removeObserver(T o); void removeAllObservers(); void
订阅 observer-pattern