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1. Add Devise Gem Open up your Gemfile and add this line gem 'devise' Then run; bundle install 2. Set up devise in your app Run the following command in the terminal rails g devise:install 3. Configure Devise Ensure you have defined default url options in your environments files. Open...

In order to ssh into a server your identity's public key has to be added to the list of trusted keys. Most commonly this is done per-user: ssh-copy-id -i ~/.ssh/<identity>.pub <user>@<hostname> Which can be also done manually: cat ~/.ssh/<identity>.pub | ssh <user>...

Coming from imperative languages many developers wonder how to write a for-loop that exits early as F# doesn't support break, continue or return. The answer in F# is to use tail-recursion which is a flexible and idiomatic way to iterate while still providing excellent performance. Say we want to ...

Many people don't make use of file.path when making path to a file. But if you are working across Windows, Mac and Linux machines it's usually good practice to use it for making paths instead of paste. FilePath <- file.path(AVariableWithFullProjectPath,"SomeSubfolder","SomeFileNam...

The following function is returning another function as its result which can be later assigned to a variable and called: func jediTrainer () -> ((String, Int) -> String) { func train(name: String, times: Int) -> (String) { return "\(name) has been trained in the Force \(times)...

Every object in R is assigned a class. You can use class() to find the object's class and str() to see its structure, including the classes it contains. For example: class(iris) [1] "data.frame" str(iris) 'data.frame': 150 obs. of 5 variables: $ Sepal.Length: num 5.1 4.9 4.7 4...

Often in R you'll want to know things about an object or variable you're working with. This can be useful when reading someone else's code or even your own, especially when using packages that are new to you. Suppose we create a variable a: a <- matrix(1:9, 3, 3) What data type is this? Yo...

Often data comes in tables. Generally one can divide this tabular data in wide and long formats. In a wide format, each variable has its own column. PersonHeight [cm]Age [yr]Alison17820Bob17445Carl18231 However, sometimes it is more convenient to have a long format, in which all variables are in o...

The Oracle Java Style Guide states: Modifiers should not be written out when they are implicit. (See Modifiers in Oracle Official Code Standard for the context and a link to the actual Oracle document.) This style guidance applies particularly to interfaces. Let's consider the following code ...

In this exercise, we will generate four bootstrap linear regression models and combine the summaries of these models into a single data frame. library(broom) #* Create the bootstrap data sets BootData <- lapply(1:4, function(i) mtcars[sample(1:nrow(mtcars), ...

A typical use case for SpriteKit is where the SKView fills the whole screen. To do this in Xcode's Interface Builder, first create a normal ViewController, then select the contained view and change its Class from UIView to SKView: Within the code for the View Controller, in the viewDidLoad metho...

One might argue that there are greater resource hogs in Unity than the humble string, but it is one of the easier aspects to fix early on. String operations build garbage Most string operations build tiny amounts of garbage, but if those operations are called several times over the course of a s...

The power of idling resources lies in not having to wait for some app's processing (networking, calculations, animations, etc.) to finish with sleep(), which brings flakiness and/or prolongs the tests run. The official documentation can be found here. Implementation There are three things that you...

2 Dimensional arrays 6 In ES6, we can flatten the array by the spread operator ...: function flattenES6(arr) { return [].concat(...arr); } var arrL1 = [1, 2, [3, 4]]; console.log(flattenES6(arrL1)); // [1, 2, 3, 4] 5 In ES5, we can acheive that by .apply(): function flatten(arr) { ...

This is the basic HTML file that can be used as a boilerplate when starting a project. This boilerplate uses orbit controls with damping (camera that can move around an object with deceleration effect) and creates a spinning cube. <!DOCTYPE html> <html> <head> <t...

public function drawDisplayObjectUsingBounds(source:DisplayObject):BitmapData { var bitmapData:BitmapData;//declare a BitmapData var bounds:Rectangle = source.getBounds(source);//get the source object actual size //round bounds to integer pixel values (to aviod 1px str...

One of the most common errors in compilation happens during the linking stage. The error looks similar to this: $ gcc undefined_reference.c /tmp/ccoXhwF0.o: In function `main': undefined_reference.c:(.text+0x15): undefined reference to `foo' collect2: error: ld returned 1 exit status $ So l...

Const baseString As String = "Hello World" Dim charLength As Long charLength = Len(baseString) 'charlength = 11

Const baseString As String = "Hello World" Dim byteLength As Long byteLength = LenB(baseString) 'byteLength = 22

When checking if a string is zero-length, it is better practice, and more efficient, to inspect the length of the string rather than comparing the string to an empty string. Const myString As String = vbNullString 'Prefer this method when checking if myString is a zero-length string If Len(mySt...