Tutorial by Examples: en

Filenames and autoloading

Rails files - and Ruby files in general - should be named with lower_snake_case filenames. E.g. app/controllers/application_controller.rb is the file that contains the ApplicationController class definition. Note that while PascalCase is used for class and module names, the files in which they r...

Ruby on Rails • Naming Conventions

Bounded generic types

// Only accept T and U generic types that also implement Debug fn print_objects<T: Debug, U: Debug>(a: T, b: U) { println!("A: {:?} B: {:?}", a, b); } print_objects(13, 44); // or annotated explicitly print_objects::<usize, u16>(13, 44); The bounds must cover a...

Rust • Generics

Generic functions

Generic functions allow some or all of their arguments to be parameterised. fn convert_values<T, U>(input_value: T) -> Result<U, String> { // Try and convert the value. // Actual code will require bounds on the types T, U to be able to do something with them. } If the compi...

Rust • Generics

Identify Binary Files

Git is pretty good at identifying binary files, but you can explicitly specify which files are binary. Create a .gitattributes file in the project root containing: *.png binary binary is a built-in macro attribute equivalent to -diff -merge -text.

Git • Using a .gitattributes file

Configuring line endings

Description When working with a team who uses different operating systems (OS) across the project, sometimes you may run into trouble when dealing with line endings. Microsoft Windows When working on Microsoft Windows operating system (OS), the line endings are normally of form - carriage return ...

Git • Configuration

Calculate Content Bounds (for i.e. dynamic cell heights)

A common use case for wanting to calculate the frame a label will take up is for sizing table view cells appropriately. The recommended way of doing this is using the NSString method boundingRectWithSize:options:attributes:context:. options takes String drawing options: NSStringDrawingUsesLineFr...

iOS • UILabel

Use requestAnimationFrame to fade in element

View jsFiddle: https://jsfiddle.net/HimmatChahal/jb5trg67/ Copy + Pasteable code below: <html> <body> <h1>This will fade in at 60 frames per second (or as close to possible as your hardware allows)</h1> <script> // Fad...

JavaScript • requestAnimationFrame

Enum definition

An enum is a set of logically related constants. Enum Size Small Medium Large End Enum Public Sub Order(shirtSize As Size) Select Case shirtSize Case Size.Small ' ... Case Size.Medium ' ... Case Size.Large ' ....

Visual Basic .NET Language • Enum

Builder Pattern / C# / Fluent Interrface

public class Email { public string To { get; set; } public string From { get; set; } public string Subject { get; set; } public string Body { get; set; } } public class EmailBuilder { private readonly Email _email; public EmailBuilder() { _email = ...

Design patterns • Builder Pattern

No return statement for a function with a non-void return type

Omitting the return statement in a function which is has a return type that is not void is undefined behavior. int function() { // Missing return statement } int main() { function(); //Undefined Behavior } Most modern day compilers emit a warning at compile time for this kind o...

C++ • Undefined Behavior

Listening to Changes of contenteditable

Events that work with most form elements (e.g., change, keydown, keyup, keypress) do not work with contenteditable. Instead, you can listen to changes of contenteditable contents with the input event. Assuming contenteditableHtmlElement is a JS DOM object that is contenteditable: contenteditableH...

JavaScript • execCommand and contenteditable

Rename Folders

To rename a folder from oldName to newName git mv directoryToFolder/oldName directoryToFolder/newName Followed by git commit and/or git push If this error occurs: fatal: renaming 'directoryToFolder/oldName' failed: Invalid argument Use the following command: git mv directoryToFolder/oldN...

Git • Renaming

Sorting sequence containers by overloaded less operator

If no ordering function is passed, std::sort will order the elements by calling operator< on pairs of elements, which must return a type contextually convertible to bool (or just bool). Basic types (integers, floats, pointers etc) have already build in comparison operators. We can overload this ...

C++ • Sorting

Sorting sequence containers using compare function

// Include sequence containers #include <vector> #include <deque> #include <list> // Insert sorting algorithm #include <algorithm> class Base { public: // Constructor that set variable to the value of v Base(int v): variable(v) { } i...

C++ • Sorting

Sorting sequence containers using lambda expressions (C++11)

C++11 // Include sequence containers #include <vector> #include <deque> #include <list> #include <array> #include <forward_list> // Include sorting algorithm #include <algorithm> class Base { public: // Constructor that set variable to the va...

C++ • Sorting

Deciding between `T`, `? super T`, and `? extends T`

The syntax for Java generics bounded wildcards, representing the unknown type by ? is: ? extends T represents an upper bounded wildcard. The unknown type represents a type that must be a subtype of T, or type T itself. ? super T represents a lower bounded wildcard. The unknown type repres...

Java Language • Generics

Remove non alphanumeric characters from string

public string Remove() { string input = "Hello./!"; return Regex.Replace(input, "[^a-zA-Z0-9]", ""); }

.NET Framework • Regular Expressions (System.Text.RegularExpressions)

Extension methods as strongly typed wrappers

Extension methods can be used for writing strongly typed wrappers for dictionary-like objects. For example a cache, HttpContext.Items at cetera... public static class CacheExtensions { public static void SetUserInfo(this Cache cache, UserInfo data) => cache["UserInfo"] ...

C# Language • Extension Methods

Enabling EdgeCache

In order to enable EdgeCache, set the following HTTP response headers (Do not deviate from this exact format): Cache-Control header to public, max-age=X where: X = the number of seconds that you want the response to be cached for X > 60 seconds X < 365*24*60*60 Set the Pragma he...

google-app-engine • EdgeCache

Get updates when a user's location changes

You can also receive regular updates of the user's location; for example, as they move around while using a mobile device. Location tracking over time can be very sensitive, so be sure to explain to the user ahead of time why you're requesting this permission and how you'll use the data. if (naviga...

JavaScript • Geolocation