Tutorial by Examples: const

class Person { [string] $Name [int] $Age Person([string] $Name) { $this.Name = $Name } Person([string] $Name, [int]$Age) { $this.Name = $Name $this.Age = $Age } }

You can't reassign constants. const foo = "bar"; foo = "hello"; Prints: Uncaught TypeError: Assignment to constant.

Declaring a variable const only prevents its value from being replaced by a new value. const does not put any restrictions on the internal state of an object. The following example shows that a value of a property of a const object can be changed, and even new properties can be added, because the ob...

You can initialize a constant by using the const keyword. const foo = 100; const bar = false; const person = { name: "John" }; const fun = function () = { /* ... */ }; const arrowFun = () => /* ... */ ; Important You must declare and initialize a constant in the same statement....

You can create a tuple and use a switch like so: var str: String? = "hi" var x: Int? = 5 switch (str, x) { case (.Some,.Some): print("Both have values") case (.Some, nil): print("String has a value") case (nil, .Some): print("Int has a value&...

Getting the Constructor Object You can obtain Constructor class from the Class object like this: Class myClass = ... // get a class object Constructor[] constructors = myClass.getConstructors(); Where the constructors variable will have one Constructor instance for each public constructor decl...

The const keyword declares a global constant binding. const DEADBEEF: u64 = 0xDEADBEEF; fn main() { println("{:X}", DEADBEEF); } This outputs DEADBEEF

__construct() is the most common magic method in PHP, because it is used to set up a class when it is initialized. The opposite of the __construct() method is the __destruct() method. This method is called when there are no more references to an object that you created or when you force its deletion...

Constructor functions are functions designed to construct a new object. Within a constructor function, the keyword this refers to a newly created object which values can be assigned to. Constructor functions "return" this new object automatically. function Cat(name) { this.name = name;...

9.0 // Since the anchor system simply returns constraints, you still need to add them somewhere. View.AddConstraints( new[] { someLabel.TopAnchor.ConstraintEqualTo(TopLayoutGuide.GetBottomAnchor()), anotherLabel.TopAnchor.ConstraintEqualTo(someLabel.BottomAnchor, 6), ...

// Using Visual Format Language requires a special look-up dictionary of names<->views. var views = new NSDictionary( nameof(someLabel), someLabel, nameof(anotherLabel), anotherLabel, nameof(oneMoreLabel), oneMoreLabel ); // It can also take a look-up dictionary for metrics (...

You can make an UILabel with a dynamic height using auto layout. You need to set the numberOfLines to zero (0), and add a minimal height by setting up a constraints with a relation of type .GreaterThanOrEqual on the .Height attribute iOS 6 Swift label.numberOfLines = 0 let heightConstraint = ...

By default all datetime objects are naive. To make them timezone-aware, you must attach a tzinfo object, which provides the UTC offset and timezone abbreviation as a function of date and time. Fixed Offset Time Zones For time zones that are a fixed offset from UTC, in Python 3.2+, the datetime mod...

Objects will often depend on other objects. Instead of creating the dependency in the constructor, the dependency should be passed into the constructor as a parameter. This ensures there is not tight coupling between the objects, and enables changing the dependency upon class instantiation. This has...

Unlike C++ in C# you can call a virtual method from class constructor (OK, you can also in C++ but behavior at first is surprising). For example: abstract class Base { protected Base() { _obj = CreateAnother(); } protected virtual AnotherBase CreateAnother() { ...

In Python 2, an octal literal could be defined as >>> 0755 # only Python 2 To ensure cross-compatibility, use 0o755 # both Python 2 and Python 3

In this example we use the constructor to declare a public property position and a protected property speed in the base class. These properties are called Parameter properties. They let us declare a constructor parameter and a member in one place. One of the best things in TypeScript, is automatic ...

The if construct (called a block IF statement in FORTRAN 77) is common across many programming languages. It conditionally executes one block of code when a logical expression is evaluated to true. [name:] IF (expr) THEN block [ELSE IF (expr) THEN [name] block] [ELSE [name] block] ...

Class constants provide a mechanism for holding fixed values in a program. That is, they provide a way of giving a name (and associated compile-time checking) to a value like 3.14 or "Apple". Class constants can only be defined with the const keyword - the define function cannot be used in...

If MsgBox("Click OK") = vbOK Then can be used in place of If MsgBox("Click OK") = 1 Then in order to improve readability. Use Object Browser to find available VB constants. View → Object Browser or F2 from VB Editor. Enter class to search View members available ...