Tutorial by Examples: io

Most of the questions around ownership come up when writing functions. When you specify the types of a function's arguments, you may choose how that value is passed in. If you only need read-only access, you can take an immutable reference: fn foo(x: &String) { // foo is only authorized to...

After Successfully installing Xamarin Studio on OS X. It's time for the first Hello World Application. Hello World Application: Xamarin.Forms What is Xamarin Forms : Xamarin.Forms is a new library that enables you to build native UIs for iOS, Android and Windows Phone from a single, shared C# c...

Because generating documentation is based on markdown, you have to do 2 things : 1/ Write your doctest and make your doctest examples clear to improve readability (It is better to give a headline, like "examples" or "tests"). When you write your tests, do not forget to give 4 s...

A dictionary object has the method copy. It performs a shallow copy of the dictionary. >>> d1 = {1:[]} >>> d2 = d1.copy() >>> d1 is d2 False >>> d1[1] is d2[1] True

In functional programming languages like F# null values are considered potentially harmful and poor style (non-idiomatic). Consider this C# code: string x = SomeFunction (); int l = x.Length; x.Length will throw if x is null let's add protection: string x = SomeFunction (); int l = x ...

Error handling is important but can make an elegant algorithm into a mess. Railway Oriented Programming (ROP) is used to make error handling elegant and composable. Consider the simple function f: let tryParse s = let b, v = System.Int32.TryParse s if b then Some v else None let f (g : ...

I create a file called database-servlet.xml somewhere on the classpath. Initially your config file will look like this: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/...

One of the easiest examples of using shared services is when we want to store some data from a given page of our application, and then get that data again but from another page. One option could be to send that data as a parameter (for instance, if one page calls the other one) but if we want to us...

We have 2 way, we can install Universal app in windows 10 devices (OS/Phone). One app works for both mobile and OS 1 Install using Power Shell command Step 1: Make sure app not have any error and developed, then right click on Universal app project in solution explorer. Step 2: Select Store and C...

We can use $q to defer operations to the future while having a pending promise object at the present, by using $q.defer we create a promise that will either resolve or reject in the future. This method is not equivalent of using the $q constructor, as we use $q.defer to promisify an existing routin...

This will rollback both inserts due to an invalid datetime: BEGIN TRANSACTION BEGIN TRY INSERT INTO dbo.Sale(Price, SaleDate, Quantity) VALUES (5.2, GETDATE(), 1) INSERT INTO dbo.Sale(Price, SaleDate, Quantity) VALUES (5.2, 'not a date', 1) COMMIT TRANSACTION END TRY BEG...

Continuing on the mtcars example, here is a simple way to produce a plot of your linear regression that is potentially suitable for publication. First fit the linear model and fit <- lm(mpg ~ wt, data = mtcars) Then plot the two variables of interest and add the regression line within the d...

ALTER TABLE tbl MODIFY COLUMN type ENUM('fish','mammal','bird','insect'); Notes As with all cases of MODIFY COLUMN, you must include NOT NULL, and any other qualifiers that originally existed, else they will be lost. If you add to the end of the list and the list is under 256 items, the ALTER...

Haskell supports many forms of concurrency and the most obvious being forking a thread using forkIO. The function forkIO :: IO () -> IO ThreadId takes an IO action and returns its ThreadId, meanwhile the action will be run in the background. We can demonstrate this quite succinctly using ghci: ...

using System; using System.Linq; using System.Security.Cryptography; namespace YourCryptoNamespace { /// <summary> /// Salted password hashing with PBKDF2-SHA1. /// Compatibility: .NET 3.0 and later. /// </summary> /// <remarks>See http://crackstation.net/h...

(.) lets us compose two functions, feeding output of one as an input to the other: (f . g) x = f (g x) For example, if we want to square the successor of an input number, we can write ((^2) . succ) 1 -- 4 There is also (<<<) which is an alias to (.). So, (+ 1) <<&lt...

Control.Category defines (>>>), which, when specialized to functions, is -- (>>>) :: Category cat => cat a b -> cat b c -> cat a c -- (>>>) :: (->) a b -> (->) b c -> (->) a c -- (>>>) :: (a -> b) -> (b -> c) -> (a -> c...

It is good practice to combine JS files together and minify them. For larger project there could be hundreds of JS files and it adds unnecessary latency to load each file separately from the server. For angular minification it is required to to have all functions annotated. That in necessary for An...

Sometimes it's useful to be able to extend a class with new functions. For example let's suppose that a string should be converted to a camel case string. So we need to tell TypeScript, that String contains a function called toCamelCase, which returns a string. interface String { toCamelCase()...

In explicit wait, you expect for a condition to happen. For example you want to wait until an element is clickable. Here is a demonstration of a few common problems. Please note: In all of these examples you can use any By as a locator, such as classname, xpath, link text, tag name or cssSelector ...