useState setter doesn’t provide a callback after state update is done like setState does in React class components. In order to replicate the same behaviour, you can make use of the a similar pattern like componentDidUpdate lifecycle method in React class components with useEffect using Hooks useEffect hooks takes the second parameter as an array … Read more
Also, your compare function is incorrect. It needs to return -1, 0, or 1, not a boolean as you have it. The correct compare function would be: def compare(item1, item2): if fitness(item1) < fitness(item2): return -1 elif fitness(item1) > fitness(item2): return 1 else: return 0 # Calling list.sort(key=compare)
var myCallback = function(data) { console.log(‘got data: ‘+data); }; var usingItNow = function(callback) { callback(‘get it?’); }; Now open node or browser console and paste the above definitions. Finally use it with this next line: usingItNow(myCallback); With Respect to the Node-Style Error Conventions Costa asked what this would look like if we were to honor … Read more
First and foremost, I highly suggest using a profiler or atleast use timeit. However if you wanted to write your own timing method strictly to learn, here is somewhere to get started using a decorator. Python 2: def timing(f): def wrap(*args): time1 = time.time() ret = f(*args) time2 = time.time() print ‘%s function took %0.3f … Read more
Looks like you’ve got some answers to this, however I think there is something worth mentioning here that will greatly simplify your code. jQuery introduced the $.when in v1.5. It looks like: $.when($.ajax(…), $.ajax(…)).then(function (resp1, resp2) { //this callback will be fired once all ajax calls have finished. }); Didn’t see it mentioned here, hope … Read more
async/await is not magic. An async function is a function that can unwrap Promises for you, so you’ll need api.on() to return a Promise for that to work. Something like this: function apiOn(event) { return new Promise(resolve => { api.on(event, response => resolve(response)); }); } Then async function test() { return await apiOn( ‘someEvent’ ); … Read more
Short answer: For maximum flexibility, you can store the callback as a boxed FnMut object, with the callback setter generic on callback type. The code for this is shown in the last example in the answer. For a more detailed explanation, read on. “Function pointers”: callbacks as fn The closest equivalent of the C++ code … Read more
In many cases, you have an interface and pass along an object that implements it. Dialogs for example have the OnClickListener. Just as a random example: // The callback interface interface MyCallback { void callbackCall(); } // The class that takes the callback class Worker { MyCallback callback; void onEvent() { callback.callbackCall(); } } // … Read more
In Javascript, there are synchronous and asynchronous functions. Synchronous Functions Most functions in Javascript are synchronous. If you were to call several synchronous functions in a row doSomething(); doSomethingElse(); doSomethingUsefulThisTime(); they will execute in order. doSomethingElse will not start until doSomething has completed. doSomethingUsefulThisTime, in turn, will not start until doSomethingElse has completed. Asynchronous Functions … Read more
You can just say callback(); Alternately you can use the call method if you want to adjust the value of this within the callback. callback.call( newValueForThis); Inside the function this would be whatever newValueForThis is.