closures

问题 I am trying to pass a lambda as parameter to a function but once I attempt to access a variable inside the lambda which was declared outside, the build fails: error: no matching function for call to 'AWS::subscribe(char [128], mainTask(void*)::<lambda(AWS_IoT_Client*, char*, uint16_t, IoT_Publish_Message_Params*, void*)>)' I was thinking that the [&] would take care of capturing variables. I also tried [=] as well as [someVar] , [&someVar] . I'm using C++11. char someVar[128]; aws->subscribe(

问题 Meteor will wrap an immediately-invoked function expression (IFFE) around the contents of any JS file, to ensure that there are no namespace conflicts between files. I am at the very early stage of a project which uses a beta npm module. I would like to be able to run code directly from the browser console, which has global scope. Is there a way to ask Meteor nicely not to wrap all my scripts in an IFFE, so that I can create global functions and access global variables, and so understand more

问题 I am trying a piece of code from the question in Lexical closures in Python flist = [] for i in xrange(3): def func(x): return x*i flist.append(func) for f in flist: print f.func_closure The output is: None None None Shouldn't it be?: (<cell at 0x9222d94: int object at 0x8cabdbc>,) (<cell at 0x9222d94: int object at 0x8cabdbc>,) (<cell at 0x9222d94: int object at 0x8cabdbc>,) I have got the above output using the following code: flist = [] def actualFact(): for i in xrange(3): def func(x):

问题 I am trying to create a struct like this in Rust: pub struct Struct<T, F> where T: Eq, T: Hash, F: Fn() -> T { hashMap: HashMap<T, F>, value: T, } My constructor looks like this: pub fn new(init_value: T) -> Struct<T, F> { Struct { hashMap: HashMap::new(), value: init_state, } } However when trying to instantiate the class, using let a = Struct::<MyEnum>::new(MyEnum::Init); , the compiler complains that the generics needs two arguments ( expected 2 type arguments, found 1 ) I saw here that

问题 I would like to be able to do something like this: def closure = { def a // create new variable, but ONLY if not created yet if (a == null) { a = 0 } a++ print a } closure() // prints 1 closure() // prints 2 closure() // prints 3, etc... I want to create the variable INSIDE the closure, not in outer scope. 回答1: This may be an invalid answer but the outer scope doesn't need to be global; it can be inside a function for example, or even an anonymous function like: def closure = { def a return {

问题 Here's what I'd really like to do: Outage.joins{eval "unit.plant"} I'm going to have a string that represents a squeel keypath . I'd like to send this string into a join statement. But here's what I get as an error: #<Class:0x639e328>: unknown class: Squeel::Nodes::Function I've tried: Outage.joins{"unit.plant"} But that does not work... what am I missing? I don't see any documentation on this on the github page: https://github.com/ernie/squeel/ Thank you for any help! Update: I've found a

问题 I have a function with a completion handler, returning one parameter or more. In a client, when executing a completion handler, I'd like to have an unowned reference to self , as well as having access to the parameter passed. Here is the Playground example illustrating the issue and the goal I'm trying to achieve. import UIKit struct Struct { func function(completion: (String) -> ()) { completion("Boom!") } func noArgumentsFunction(completion: () -> Void) { completion() } } class Class2 {

问题 How do i trace the values of local variables in closure, and also the execution flow of closures in firebug. or is there any other tools that is specifically for debugging closures. 回答1: Yes. You can debug the javascript closure with Firebug. On Script tab, you can see all the object instances as well as the state of the whole object. Please, Find it below the screenshot of firebug showing local variables in closure. (source: pengbos.com) If you want to learn more read this here and practice

问题 I'm using the Google Maps API to plot several points on a map. However, in the click event function below, i is always set to 4, i.e. its value after iterating the loop: // note these are actual addresses in the real page var addresses = new Array( "addr 1", "addr 2", "addr 3", "addr 4" ); for (var i = 0; i < addresses.length; i++) { geocoder.getLatLng(addresses[i], function(point) { if (point) { var marker = new GMarker(point); map.addOverlay(marker); map.setCenter(point, 13); GEvent

问题 i'm working with Alamofire library, i've noticed that they use this syntax func download(method: Alamofire.Method, URLString: URLStringConvertible, headers: [String : String]? = default, #destination: Alamofire.Request.DownloadFileDestination) -> Alamofire.Request that takes 4 parameters as input but if you go to the documentation to call the method they use the following Alamofire.download(.GET, "http://httpbin.org/stream/100") { temporaryURL, response in let fileManager = NSFileManager