Tutorial by Examples: ch

An observable is created from the TextChanged event of the TextBox. Also any input is only selected if it's different from the last input and if there was no input within 0.5 seconds. The output in this example is sent to the console. Observable .FromEventPattern(textBoxInput, "TextChan...

The NotifyPropertyChangedBaseclass below defines a generic Set method that can be called from any derived type. public class NotifyPropertyChangedBase : INotifyPropertyChanged { protected void RaisePropertyChanged([CallerMemberName] string propertyName = null) => PropertyChanged?.Invo...

To prevent memory leaks, one should not forget to close an input stream or an output stream whose job is done. This is usually done with a try-catch-finally statement without the catch part: void writeNullBytesToAFile(int count, String filename) throws IOException { FileOutputStream out = null...

CREATE SCHEMA dvr AUTHORIZATION Owner CREATE TABLE sat_Sales (source int, cost int, partid int) GRANT SELECT ON SCHEMA :: dvr TO User1 DENY SELECT ON SCHEMA :: dvr to User 2 GO

ALTER SCHEMA dvr TRANSFER dbo.tbl_Staging; GO This would transfer the tbl_Staging table from the dbo schema to the dvr schema

DROP SCHEMA dvr

The Deque is the only Python data structure with fast Queue operations. (Note queue.Queue isn't normally suitable, since it's meant for communication between threads.) A basic use case of a Queue is the breadth first search. from collections import deque def bfs(graph, root): distances = {}...

Sometimes, the latest tagged version of a package is buggy or is missing some required features. Advanced users may wish to update to the latest development version of a package (sometimes referred to as the "master", named after the usual name for a development branch in Git). The benefit...

Search for a lemma when you know what its conclusion ought to be: Coq < SearchPattern (S _ <= _). le_n_S: forall n m : nat, n <= m -> S n <= S m You can also search on a partial conclusion (the conclusion and one or several last hypotheses). Coq < Require Import Arith. Coq &...

Swift Add this extension to UIImage : extension UIImage { func maskWithColor(color: UIColor) -> UIImage? { let maskImage = self.CGImage let width = self.size.width let height = self.size.height let bounds = CGRectMake(0, 0, width, height) ...

How it works The string.gmatch function will take an input string and a pattern. This pattern describes on what to actually get back. This function will return a function which is actually an iterator. The result of this iterator will match to the pattern. type(("abc"):gmatch ".&quo...

When used inside a double-quoted string, the escape character (backtick `) reperesents a special character. `0 #Null `a #Alert/Beep `b #Backspace `f #Form feed (used for printer output) `n #New line `r #Carriage return `t #Horizontal tab `v #Vertical tab (used for pri...

public static async Task PostAsync(this Uri uri, object value) { var content = new ObjectContext(value.GetType(), value, new JsonMediaTypeFormatter()); using (var client = new HttpClient()) { return await client.PostAsync(uri, content); } } . . . var uri = new ...

public static async Task<TResult> GetAnsync<TResult>(this Uri uri) { using (var client = new HttpClient()) { var message = await client.GetAsync(uri); if (!message.IsSuccessStatusCode) throw new Exception(); return message.ReadAsAsyn...

In Symfony, the built-in ChoiceType (and EntityType or DocumentType extending it), basicaly work with a constant choice list. If you want to make it work with ajax calls, you have to change them to accept any sumitted extra choices. How to start with an empty choice list ? When you build your...

When you define a class or module, the implicit receiver becomes a reference to the class itself. For example: puts "I am #{self}" class Example puts "I am #{self}" end Executing the above code will print: "I am main" "I am Example"

HTML Import caching will sometimes mean that changes made to HTML files that get imported do not get reflected upon browser refresh. Take the following import as an example: <link rel="import" href="./my-element.html"> If a change is done to my-element.html after previo...

If you want to execute synchronous code asynchronous (for example CPU extensive calculations), you can use Task.Run(() => {}). public async Task DoStuffAsync() { await DoCpuBoundWorkAsync(); } private async Task DoCpuBoundWorkAsync() { await Task.Run(() => { fo...

@IBAction func axisChange(sender: UISwitch) { UIView.animateWithDuration(1.0) { self.updateConstraintsForAxis() } } The updateConstraintForAxis function just sets the axis of the stack view containing the two image views: private func updateConstraintsForAxis() { if (axi...

There are four primary useful functions for regular expressions, all of which take arguments in needle, haystack order. The terminology "needle" and "haystack" come from the English idiom "finding a needle in a haystack". In the context of regexes, the regex is the need...