initializer

问题 Newbie here. I am looking at company code. It appears that there are NO member variables in class A yet in A's constructor it initializes an object B even though class A does not contain any member variable of type B (or any member variable at all!). I guess I don't understand it enough to even ask a question...so what's going on here!? My intuition is that you need a variable before you even try to initialize it. How is it possible (or what good does it do) to initialize an object without

问题 I would like to run an rspec before block to set some stuff up before the Rails initializers run, so I can test what an initializer should be doing. Is this possible? 回答1: If the logic in your initializers is complex enough it should be tested, you should extract it into a helper that you can isolate and test without being in the context of the initializer. complex_initializer.rb config.database.foo = calculate_hard_stuff() config.database.bar = other_stuff() You could extract that into a

问题 I have a @IBDesignable class Fancy:UIButton I want to addTarget(self, action:#selector(blah), forControlEvents: UIControlEvents.TouchUpInside) So where in UIButton should that be done? Where is the best place for addTarget ? 1 - I have seen layoutSubviews suggested - is that right? Note - experimentation shows that a problem with layoutSubviews is that, of course, it can be called often, whenever things move around. It would be a bad idea to "addTarget" more than once. 2 - didMoveToSuperview

问题 I have a class for a linked list declared like this: class LinkedNode<T> { let data: T var next: LinkedNode<T>? func traverseList(process: (LinkedNode<T>) -> ()) { ... } } What I want to do is extend Array to have an initialiser that converts my LinkedNode class to an array of linked nodes. I tried this: extension Array where Element == LinkedNode<T> { init(node: LinkedNode<T>) { var result = [LinkedNode<T>]() traverseList { result.append($0) } return result } } But that gives errors that T

问题 I'm attempting to integrate a twitter feed into my Rails 4 application using this gem. I've read the documentation on the github page but I'm running into a problem when trying to use a method in my view. I have the following in an initializer file named twitter_init.rb (with my auth info): client = Twitter::Streaming::Client.new do |config| config.consumer_key = "YOUR_CONSUMER_KEY" config.consumer_secret = "YOUR_CONSUMER_SECRET" config.access_token = "YOUR_ACCESS_TOKEN" config.access_token

问题 I have a problem with the following code. As we can see I have already handled the exception thrown by A's constructor in C's constructor, why should I bother to catch and handle the exception again in the main function? #include <iostream> class WException : public std::exception { public: WException( const char* info ) : std::exception(info){} }; class A { public: A( int a ) : a(a) { std::cout << "A's constructor run." << std::endl; throw WException("A constructor throw exception."); }

问题 I have a Swift class that has a constant ivar (are they called instance constants now?). To set the value to this constant, I need to call an initializer of the desired object and pass itself. However, I am not allowed to as I need to initialize all values first, then call super.init() and after that I am allowed to access self . So what to do in this case? class Broadcaster: NSObject, CBPeripheralManagerDelegate { let broadcastID: NSUUID let bluetoothManager: CBPeripheralManager init

问题 While crafting the Passenger-Monit plugin, I thought that it'll be most appropriate to use the initializer, i.e. module PassengerMonit class Railtie < Rails::Railtie initializer "my_plugin.some_init_task" do # my initialization tasks end end end However, for some reason the code in the block was never executed. I finally made a work-around with config.before_initialize {} but I'm curious, why the initializer wasn't executed. What could have prevented it from running? 回答1: In your gemfile, did

问题 My webapp needs to encrypt its session data. What I setup is: config/initializers/encryptor.rb: require 'openssl' require 'myapp/encryptor' MyApp::Encryptor.config[ :random_key ] = OpenSSL::Random.random_bytes( 128 ) Session.delete_all app/models/session.rb: require 'attr_encrypted' class Session < ActiveRecord::Base attr_accessible :session_id, :data attr_encryptor :data, :key => proc { MyApp::Encryptor.config[ :random_key ] }, :marshal => true # Rest of model stuff end That all works great,

问题 Couldn't find an answer to this question. It must be obvious, but still. I try to use initializer in this simplified example: MyNode newNode = new MyNode { NodeName = "newNode", Children.Add(/*smth*/) // mistake is here }; where Children is a property for this class, which returns a list. And here I come across a mistake, which goes like 'Invalid initializer member declarator'. What is wrong here, and how do you initialize such properties? Thanks a lot in advance! 回答1: You can't call methods