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Ember comes with a built in helper that will provide computed properties for the status of an asynchronous task. Pros Built in – no need for an addon. Can be managed in the life cycle of a component. Provides convenient state properties that can drive the template logic. Cons Must be wra...

A custom extraction can be written by implementing the unapply method and returning a value of type Option: class Foo(val x: String) object Foo { def unapply(foo: Foo): Option[String] = Some(foo.x) } new Foo("42") match { case Foo(x) => x } // "42" The retur...

3.0 In Swift 3 there are multiple access-levels. This example uses them all except for open: public struct Car { public let make: String let model: String //Optional keyword: will automatically be "internal" private let fullName: String fileprivate var otherName...

public class SuperClass { private func secretMethod() {} } internal class SubClass: SuperClass { override internal func secretMethod() { super.secretMethod() } }

struct Square { private(set) var area = 0 var side: Int = 0 { didSet { area = side*side } } } public struct Square { public private(set) var area = 0 public var side: Int = 0 { didSet { area = side*side } ...

To add a new indexed column email to the users table, run the command: rails generate migration AddEmailToUsers email:string:index This will generate the following migration: class AddEmailToUsers < ActiveRecord::Migration[5.0] def change add_column :users, :email, :string add_i...

To remove existing column name from users table, run the command: rails generate migration RemoveNameFromUsers name:string This will generate the following migration: class RemoveNameFromUsers < ActiveRecord::Migration[5.0] def change remove_column :users, :name, :string end end ...

// Execute a command a capture standard out. exec.Command creates the command // and then the chained Output method gets standard out. Use CombinedOutput() // if you want both standard out and standerr output out, err := exec.Command("echo", "foo").Output() if err != nil { ...

cmd := exec.Command("sleep", "5") // Does not wait for command to complete before returning err := cmd.Start() if err != nil { log.Fatal(err) } // Wait for cmd to Return err = cmd.Wait() log.Printf("Command finished with error: %v", err)

./mongo localhost:27017/mydb myjsfile.js Explanation: This operation executes the myjsfile.js script in a mongo shell that connects to the mydb database on the mongod instance accessible via the localhost interface on port 27017. localhost:27017 is not mandatory as this is the default port mongo...

Functions can be written using several types of syntax function name() integer name name = 42 end function integer function name() name = 42 end function function name() result(res) integer res res = 42 end function Functions return values through a function result....

In the VBA Editor window, from the Tools menu select "Options": Then in the "Editor" tab, make sure that "Require Variable Declaration" is checked: Selecting this option will automatically put Option Explicit at the top of every VBA module. Small note: This is ...

Quite often, the reason why code has been written in a for loop is to compute values from 'nearby' ones. The function bsxfun can often be used to do this in a more succinct fashion. For example, assume that you wish to perform a columnwise operation on the matrix B, subtracting the mean of each col...

The things Array contains values of Any type. let things: [Any] = [1, "Hello", 2, true, false, "World", 3] We can extract values of a given type and create a new Array of that specific type. Let's say we want to extract all the Int(s) and put them into an Int Array in a safe ...

To write the traditional Hello World program in Rust, create a text file called hello.rs containing the following source code: fn main() { println!("Hello World!"); } This defines a new function called main, which takes no parameters and returns no data. This is where your progra...

Module is a collection of type declarations, data declarations and procedures. The basic syntax is: module module_name use other_module_being_used ! The use of implicit none here will set it for the scope of the module. ! Therefore, it is not required (although considered good practice...

The module cmath includes additional functions to use complex numbers. import cmath This module can calculate the phase of a complex number, in radians: z = 2+3j # A complex number cmath.phase(z) # 0.982793723247329 It allows the conversion between the cartesian (rectangular) and polar repr...

Python has built-in support for complex arithmetic. The imaginary unit is denoted by j: z = 2+3j # A complex number w = 1-7j # Another complex number Complex numbers can be summed, subtracted, multiplied, divided and exponentiated: z + w # (3-4j) z - w # (1+10j) z * w # (23-11j) z / w # (...

Key Value Coding is integrated into NSObject using NSKeyValueCoding protocol. What this means? It means that any id object is capable of calling valueForKey method and its various variants like valueForKeyPath etc. ' It also means that any id object can invoke setValue method and its various vari...

Swift label1.layer.shadowOffset = CGSize(width: 3, height: 3) label1.layer.shadowOpacity = 0.7 label1.layer.shadowRadius = 2 Swift 3 label1.layer.shadowOffset = CGSize(width: 3, height: 3) label1.layer.shadowOpacity = 0.7 label1.layer.shadowRadius = 2 Objective-C label1.layer.shadowOffs...