Tutorial by Examples: class

In addition to the standard makeLenses function for generating Lenses, Control.Lens.TH also offers the makeClassy function. makeClassy has the same type and works in essentially the same way as makeLenses, with one key difference. In addition to generating the standard lenses and traversals, if the ...
In Haskell, data types can have arguments just like functions. Take the Maybe type for example. Maybe is a very useful type which allows us to represent the idea of failure, or the possiblity thereof. In other words, if there is a possibility that a computation will fail, we use the Maybe type ther...
C++17 C++17 introduces std::string_view, which is simply a non-owning range of const chars, implementable as either a pair of pointers or a pointer and a length. It is a superior parameter type for functions that requires non-modifiable string data. Before C++17, there were three options for this: ...
Declare public variables and methods type in the interface to define how other typescript code can interact with it. interface ISampleClassInterface { sampleVariable: string; sampleMethod(): void; optionalVariable?: string; } Here we create a class that implements the interface. ...
A class in Scala is a 'blueprint' of a class instance. An instance contains the state and behavior as defined by that class. To declare a class: class MyClass{} // curly braces are optional here as class body is empty An instance can be instantiated using new keyword: var instance = new MyClas...
Code that uses generics has many benefits over non-generic code. Below are the main benefits Stronger type checks at compile time A Java compiler applies strong type checking to generic code and issues errors if the code violates type safety. Fixing compile-time errors is easier than fixing runt...
Using iris dataset: import sklearn.datasets iris_dataset = sklearn.datasets.load_iris() X, y = iris_dataset['data'], iris_dataset['target'] Data is split into train and test sets. To do this we use the train_test_split utility function to split both X and y (data and target vectors) randomly w...
A method defined in an interface is by default public abstract. When an abstract class implements an interface, any methods which are defined in the interface do not have to be implemented by the abstract class. This is because a class that is declared abstract can contain abstract method declaratio...
The special attribute __name__ of a function, class or module is a string containing its name. import os class C: pass def f(x): x += 2 return x print(f) # <function f at 0x029976B0> print(f.__name__) # f print(C) # <class '__main__.C'> print(C.__name__...
class Result<T> { constructor(public wasSuccessful: boolean, public error: T) { } public clone(): Result<T> { ... } } let r1 = new Result(false, 'error: 42'); // Compiler infers T to string let r2 = new Result(false, 42); // Compiler infers T...
Create generic class instance: var stringRunnable = new Runnable<string>(); Run generic function: function runSafe<T extends Runnable<U>, U>(runnable: T); // Specify the generic types: runSafe<Runnable<string>, string>(stringRunnable); // Let typescript figu...
Haskell supports a notion of class extension. For example, the class Ord inherits all of the operations in Eq, but in addition has a compare function that returns an Ordering between values. Ord may also contain the common order comparison operators, as well as a min method and a max method. The =&...
ABAP Classes can be declared Globally or Locally. A global class can be used by any object within the ABAP repository. By contrast, a local class can only be used within the scope it is declared. CLASS lcl_abap_class DEFINITION. PUBLIC SECTION. PROTECTED SECTION. PRIVATE SECTION. ENDCLASS...
Type type = obj.GetType(); //To restrict return properties. If all properties are required don't provide flag. BindingFlags flags = BindingFlags.Public | BindingFlags.Instance; PropertyInfo[] properties = type.GetProperties(flags); foreach (PropertyInfo property in properties) { Console...
Implicit classes make it possible to add new methods to previously defined classes. The String class has no method withoutVowels. This can be added like so: object StringUtil { implicit class StringEnhancer(str: String) { def withoutVowels: String = str.replaceAll("[aeiou]", &quo...
You can use the .Net Math class to do calculations ([System.Math]) If you want to know which methods are available you can use: [System.Math] | Get-Member -Static -MemberType Methods Here are some examples how to use the Math class: PS C:\> [System.Math]::Floor(9.42) 9 PS C:\> [System....
Let's say we have a class MyClass with no constructor argument: class MyClass In Scala we can instantiate it using below syntax: val obj = new MyClass() Or we can simply write: val obj = new MyClass But, if not paid attention, in some cases optional parenthesis may produce some unexpecte...
Information The ABSTRACT and FINAL additions to the METHODS and CLASS statements allow you to define abstract and final methods or classes. An abstract method is defined in an abstract class and cannot be implemented in that class. Instead, it is implemented in a subclass of the class. Abstra...
Let's assume that you need to show the status of a user and you have several possible CSS classes that could be used. Angular makes it very easy to choose from a list of several possible classes which allow you to specify an object list that include conditionals. Angular is able to use the correct...
Angular supports three types of expressions in the ng-class directive. 1. String <span ng-class="MyClass">Sample Text</span> Specifying an expression that evaluates to a string tells Angular to treat it as a $scope variable. Angular will check the $scope and look for a va...

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