Tutorial by Examples: construct

Assume you want to delegate to a class but you do not want to provide the delegated-to class in the constructor parameter. Instead, you want to construct it privately, making the constructor caller unaware of it. At first this might seem impossible because class delegation allows to delegate only to...

To export the type and all its constructors, one must use the following syntax: module X (Person (..)) where So, for the following top-level definitions in a file called People.hs: data Person = Friend String | Foe deriving (Show, Eq, Ord) isFoe Foe = True isFoe _ = False This module d...

This does not cover allocators. struct A {}; struct B { B()=default; B(B const&)=default; B(int){}; }; struct C { C()=delete; C(int) {}; C(C const&)=default; }; struct D { D( std::initializer_list<int> ) {}; D(D const&)=default; D()=default; }; std::variant<A,B> var_ab...

R provides two additional looping constructs, while and repeat, which are typically used in situations where the number of iterations required is indeterminate. The while loop The general form of a while loop is as follows, while (condition) { ## do something ## in loop body } whe...

A conversion that involves calling an explicit constructor or conversion function can't be done implicitly. We can request that the conversion be done explicitly using static_cast. The meaning is the same as that of a direct initialization, except that the result is a temporary. class C { std:...

Shall the property value's assignment be executed before or after the class' constructor? public class TestClass { public int TestProperty { get; set; } = 2; public TestClass() { if (TestProperty == 1) { Console.WriteLine("Shall this be e...

Use parentheses and commas to create tuples. Use one comma to create a pair. (1, 2) Use more commas to create tuples with more components. (1, 2, 3) (1, 2, 3, 4) Note that it is also possible to declare tuples using in their unsugared form. (,) 1 2 -- equivalent to (1,2) (,,) 1 2 3 ...

One can initialize a Julia array by hand, using the square-brackets syntax: julia> x = [1, 2, 3] 3-element Array{Int64,1}: 1 2 3 The first line after the command shows the size of the array you created. It also shows the type of its elements and its dimensionality (int this case Int64 ...

Classes have instance variable (dependencies), on which they call methods. Example taken from http://www.jamesshore.com/Blog/Dependency-Injection-Demystified.html for reference public class Example { private DatabaseThingie myDatabase; public Example() { myDatabase = new DatabaseTh...

Class Car ... ' Parameterless Constructor Public Sub Class_Initialize() distances_ = Array(0) End Sub ' Default initialization method that can be invoked without ' explicitly using the method name. Public Default Function Init(wheels) wheels_ = ...

/** * @var \Vendor\Module\Helper\Data */ protected $customHelper; /** * Constructor call * @param \Vendor\Module\Helper\Data $customHelper */ public function __construct( \Vendor\Module\Helper\Data $customHelper ) { $this->customHelper = $customHelper; parent::__co...

ExecutorService ExecutorService executor = Executors.newFixedThreadPool(50); It is simple and easy to use. It hides low level details of ThreadPoolExecutor. I prefer this one when number of Callable/Runnable tasks are small in number and piling of tasks in unbounded queue does not increase m...

In Julia, you can have an Array that holds other Array type objects. Consider the following examples of initializing various types of Arrays: A = Array{Float64}(10,10) # A single Array, dimensions 10 by 10, of Float64 type objects B = Array{Array}(10,10,10) # A 10 by 10 by 10 Array. Each ele...

You do not need to use double negation in if-else statements. if 'hello' puts 'hey!' else puts 'bye!' end The above code prints 'hey!' on the screen.

We can avoid providing direct access to resource intensive constructors, like for databases. public class DbConnection { private static final int MAX_CONNS = 100; private static int totalConnections = 0; private static Set<DbConnection> availableConnections = new HashSet<DbConnectio...

interface IService { void ProcessRequest(); } interface IRepository { IEnumerable<string> GetData(); } class HelloWorldRepository : IRepository { public IEnumerable<string> GetData() { return new[] { "Hello", "World" }; } ...

using System; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { var dep = new DefaultDependency(); var foo = new ClassWithDependency(dep); foo.DoSomething(); var bar = new Injected...

The Constructor Dependency Injection requires parameters in the constructor to inject dependencies. So you have to pass the values when you create a new object. public class Example { private readonly ILogging _logging; public Example(ILogging logging) { this._logging = l...

The where construct, available in Fortran90 onwards represents a masked do construct. The masking statement follows the same rules of the if statement, but is applied to all the elements of the given array. Using where allows operations to be carried out on an array (or multiple arrays of the same s...

void parallelAddition (unsigned N, const double *A, const double *B, double *C) { unsigned i; #pragma omp parallel for shared (A,B,C,N) private(i) schedule(static) for (i = 0; i < N; ++i) { C[i] = A[i] + B[i]; } } This example adds two vector (A and B into...