Tutorial by Examples: io

Functions skip class scope when looking up names

Classes have a local scope during definition, but functions inside the class do not use that scope when looking up names. Because lambdas are functions, and comprehensions are implemented using function scope, this can lead to some surprising behavior. a = 'global' class Fred: a = 'class' ...

Python Language • Variable Scope and Binding

Print out enumeration using the Image attribute

Ada 2012(TC-1) with Ada.Text_IO; procedure Main is type Fruit is (Banana, Orange, Pear); X : Fruit := Orange; begin Ada.Text_IO.Put_Line (X'Image); Ada.Text_IO.Put_Line (Pear'Image); end Main; Result ORANGE PEAR

ada • Attribute Image

Use a dict of functions

Another straightforward way to go is to create a dictionary of functions: switch = { 1: lambda: 'one', 2: lambda: 'two', 42: lambda: 'the answer of life the universe and everything', } then you add a default function: def default_case(): raise Exception('No case found!') ...

Python Language • Alternatives to switch statement from other languages

Use class introspection

You can use a class to mimic the switch/case structure. The following is using introspection of a class (using the getattr() function that resolves a string into a bound method on an instance) to resolve the "case" part. Then that introspecting method is aliased to the __call__ method to ...

Python Language • Alternatives to switch statement from other languages

Label with bindable collection of Spans

I created custom label with wrapper around FormattedText property: public class MultiComponentLabel : Label { public IList<TextComponent> Components { get; set; } public MultiComponentLabel() { var components = new ObservableCollection<TextComponent>(); ...

Xamarin.Forms • Creating custom controls

Performing an action on a view

It is possible to perform ViewActions on a view using the perform method. The ViewActions class provides helper methods for the most common actions, like: ViewActions.click() ViewActions.typeText() ViewActions.clearText() For example, to click on the view: onView(...).perform(click()); onVi...

Android • Testing UI with Espresso

Bulkification

If you do row-by-row processing in Salesforce, you'll probably reach the governor limit quickly. This is especially true with triggers and things that fire when you don't expect them. One documented method of escaping the governor limit is bulkification. Note: The following information is based on ...

Salesforce • Trigger Bulkification

Installation or Setup

Chart.js can be included in several different ways: NPM Run the following command on your NPM project directory npm install chart.js --save CDN Include a script tag in your HTML linking to the chart.js CDN <html> <body> <script type="text/javascript" s...

chart.js • Getting started with chart.js

Introduction

Ruby has three types of objects: Classes and modules which are instances of class Class or class Module. Instances of classes. Singleton Classes. Each object has a class which contains its methods: class Example end object = Example.new object.class # => Example Example.class # ...

Ruby Language • Singleton Class

Flowing execution context with AsyncLocal

When you need to pass some data from the parent task to its children tasks, so it logically flows with the execution, use AsyncLocal class: void Main() { AsyncLocal<string> user = new AsyncLocal<string>(); user.Value = "initial user"; // this does not aff...

.NET Framework • Task Parallel Library (TPL)

Basic subscription to Time.every event with 'unsubscribe'

0.18.0 Model is passed to subscriptions which means that every state change can modify subscriptions. import Html exposing ( Html, div, text, button ) import Html.Events exposing ( onClick ) import Time main : Program Never Model Msg main = Html.program { init = init ,...

Elm Language • Subscriptions

StackOverflowError & recursion to loop

If a recursive call goes "too deep", this results in a StackOverflowError. Java allocates a new frame for every method call on its thread's stack. However, the space of each thread's stack is limited. Too many frames on the stack leads to the Stack Overflow (SO). Example public static vo...

Java Language • Recursion

Getting started on iOS

Prerequisites Create a new project and add an iOS app to that project in the Firebase Console. Download and include GoogleServices-Info.plist in your application. Add Firebase Storage to your app Add the following dependency to your project's Podfile: pod 'Firebase/Storage' Run pod insta...

firebase • Storage

Packing function arguments

In functions, you can define a number of mandatory arguments: def fun1(arg1, arg2, arg3): return (arg1,arg2,arg3) which will make the function callable only when the three arguments are given: fun1(1, 2, 3) and you can define the arguments as optional, by using default values: def fun...

Python Language • List destructuring (aka packing and unpacking)

Unpacking function arguments

When you want to create a function that can accept any number of arguments, and not enforce the position or the name of the argument at "compile" time, it's possible and here's how: def fun1(*args, **kwargs): print(args, kwargs) The *args and **kwargs parameters are special parame...

Python Language • List destructuring (aka packing and unpacking)

Print out Enumeration using attribute Image

with Ada.Text_IO; procedure Main is type Fruit is (Banana, Orange, Pear); X : Fruit := Orange; begin Ada.Text_IO.Put_Line (Fruit'Image (X)); end Main; Result ORANGE

ada • Attribute Image

Exceptions in static constructors

If a static constructor throws an exception, it is never retried. The type is unusable for the lifetime of the AppDomain. Any further usages of the type will raise a TypeInitializationException wrapped around the original exception. public class Animal { static Animal() { Consol...

C# Language • Constructors and Finalizers

The Chef Documentation

You can find the Chef documentation at https://docs.chef.io/.

chef • Getting started with chef

Installation or Setup

Detailed instructions on getting material-design set up or installed.

material-design • Getting started with material-design

Remote server authentication using StringRequest through POST method

For the sake of this example, let us assume that we have a server for handling the POST requests that we will be making from our Android app: // User input data. String email = "[email protected]"; String password = "123"; // Our server URL for handling POST requests. String UR...

Android • Volley