The answer to the duplicate operation is: To solve multiple inheritance issue a class implementing two interfaces providing a default implementation for the same method name and signature must provide an implementation of the method. [Full Article] My answer to your question is: Yes, it is a form of multiple inheritance, because you can inherit … Read more
Swift Completion Handler Escaping & Non-Escaping: Assume the user is updating an app while using it. You definitely want to notify the user when it is done. You possibly want to pop up a box that says, “Congratulations, now, you may fully enjoy!” So, how do you run a block of code only after the … Read more
A couple of observations: It will always execute what’s at 1 before 2. The only way you’d get the behavior you describe is if you’re doing something else inside that for loop that is, itself, asynchronous. And if that were the case, you’d use a dispatch group to solve that (or refactor the code to … Read more
As @thg435 points out, a lambda will not encapsulate the values at that moment, but rather the scope. There are too small ways you can address this: lambda default argument “hack” [ lambda v=i: v for i in [ 1, 2, 3 ] ] Or use functools.partial from functools import partial [ partial(lambda v: v, … Read more
It’s not true that there are restrictions that prevent you from calling eval that would be missed by static-analysis: it’s just that such references to to eval run in the global scope. Note that this is a change in ES5 from ES3 where indirect and direct references to eval both ran in the local scope, … Read more
This was already planned for PHP 5.3, but For PHP 5.3 $this support for Closures was removed because no consensus could be reached how to implement it in a sane fashion. This RFC describes the possible roads that can be taken to implement it in the next PHP version. It indeed means you can refer … Read more
Optional chaining wraps whatever the result of the right side is inside an optional. So if run() returned T, then x?.run() returns T?. Since run() returns Void (a.k.a. ()), that means the whole optional chaining expression has type Void? (or ()?). When a closure has only one line, the contents of that line is implicitly … Read more
The value of i changes with each iteration of the loop. You need a closure to capture the value of i: (function(i) { my_element.onclick = function () {my_function (i)}; }(i))
Its because at the time item.help is evaluated, the loop would have completed in its entirety. Instead, you can do this with a closure: for (var i = 0; i < helpText.length; i++) { document.getElementById(helpText[i].id).onfocus = function(item) { return function() {showHelp(item.help);}; }(helpText[i]); } JavaScript doesn’t have block scope but it does have function-scope. By creating … Read more