Tutorial by Examples: def

To develop an application for iOS, you should start with an application called Xcode. There are other alternative tools you can use, but Xcode is Apple's official tool. Note, however, that it only runs on macOS. The latest official version is Xcode 8.3.3 with Xcode 9 (currently in beta) due to be re...
An interface in Kotlin can have default implementations for functions: interface MyInterface { fun withImplementation() { print("withImplementation() was called") } } Classes implementing such interfaces will be able to use those functions without reimplementing cl...
def make_animal_sound(sound = 'Cuack') puts sound end make_animal_sound('Mooo') # Mooo make_animal_sound # Cuack It's possible to include defaults for multiple arguments: def make_animal_sound(sound = 'Cuack', volume = 11) play_sound(sound, volume) end make_animal_so...
Setting a default value can be done by using Initializers (C#6) public class Name { public string First { get; set; } = "James"; public string Last { get; set; } = "Smith"; } If it is read only you can return values like this: public class Name { pu...
A class can be defined using classdef in an .m file with the same name as the class. The file can contain the classdef...end block and local functions for use within class methods. The most general MATLAB class definition has the following structure: classdef (ClassAttribute = expression, ...) Cla...
class Animal def method_missing(method, *args, &block) "Cannot call #{method} on Animal" end end => Animal.new.say_moo > "Cannot call say_moo on Animal"
If the variable contains a value of an immutable type (e.g. a string) then it is okay to assign a default value like this class Rectangle(object): def __init__(self, width, height, color='blue'): self.width = width self.height = height self.color = color d...
The Default keyword is used to execute an action when no other conditions match the input value. Example: switch('Condition') { 'Skip Condition' { 'First Action' } 'Skip This Condition Too' { 'Second Action' } Default { 'Default Action' } } Output: D...
typedef double (^Operation)(double first, double second); If you declare a block type as a typedef, you can then use the new type name instead of the full description of the arguments and return values. This defines Operation as a block that takes two doubles and returns a double. The type can b...
The default value for an enum is zero. If an enum does not define an item with a value of zero, its default value will be zero. public class Program { enum EnumExample { one = 1, two = 2 } public void Main() { var e =...
def my_mix(name,valid=true, *opt) puts name puts valid puts opt end Call as follows: my_mix('me') # 'me' # true # [] my_mix('me', false) # 'me' # false # [] my_mix('me', true, 5, 7) # 'me' # true # [5,7]
The simple answer is that it allows you to evolve an existing interface without breaking existing implementations. For example, you have Swim interface that you published 20 years ago. public interface Swim { void backStroke(); } We did a great job, our interface is very popular, there ar...
function add(a, b) return a + b end -- creates a function called add, which returns the sum of it's two arguments Let's look at the syntax. First, we see a function keyword. Well, that's pretty descriptive. Next we see the add identifier; the name. We then see the arguments (a, b) these c...
function sayHello(name) print("Hello, " .. name .. "!") end That function is a simple function, and it works well. But what would happen if we just called sayHello()? stdin:2: attempt to concatenate local 'name' (a nil value) stack traceback: stdin:2: in function ...
Functions in Common Lisp are first class values. An anonymous function can be created by using lambda. For example, here is a function of 3 arguments which we then call using funcall CL-USER> (lambda (a b c) (+ a (* b c))) #<FUNCTION (LAMBDA (A B C)) {10034F484B}> CL-USER> (defvar *fo...
When implementing more than one interface that have methods of the same name that include default implementations, it is ambiguous to the compiler which implementation should be used. In the case of a conflict, the developer must override the conflicting method and provide a custom implementation. ...
Forms can be defined, in a similar manner to models, by subclassing django.forms.Form. Various field input options are available such as CharField, URLField, IntegerField, etc. Defining a simple contact form can be seen below: from django import forms class ContactForm(forms.Form): contac...
Avoid destructive operations on quoted objects. Quoted objects are literal objects. They are possibly embedded in the code in some way. How this works and the effects of modifications are unspecified in the Common Lisp standard, but it can have unwanted consequences like modifying shared data, tryin...
Define a menu in res/menu <?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"> <item android:id="@+id/first_...

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