Tutorial by Examples: v

Any String can be evaluated at runtime. class Example def self.foo :foo end end eval "Example.foo" #=> :foo

Ruby keeps track of local variables and self variable via an object called binding. We can get binding of a scope with calling Kernel#binding and evaluate string inside a binding via Binding#eval. b = proc do local_variable = :local binding end.call b.eval "local_variable" #=&gt...

The instance_eval method is available on all objects. It evaluates code in the context of the receiver: object = Object.new object.instance_eval do @variable = :value end object.instance_variable_get :@variable # => :value instance_eval sets self to object for the duration of the co...

There are a couple of builtin viewports, that each do different things. Here is a list of the names, and their descriptions: Viewport NameDescriptionStretchViewportWill stretch the screen. No black bars, but aspect ratio might be off.FitViewportWill maximize it's size based on the aspect ratio. Cou...

You can make your very own custom viewport. It may have black bars, and it may or may not keep it's aspect ratio, depending on how you program it. A custom viewport would look something like this: public class Tutorial extends Viewport. You would need to override update(width, height), but that's it...

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In this example you will learn how to generate RSA-OAEP key pair and how to convert private key from this key pair to base64 so you can use it with OpenSSL etc. Please note that this process can also be used for public key you just have to use prefix and suffix below: -----BEGIN PUBLIC KEY----- --...

So, have you ever wondered how to use your PEM RSA key pair that was generated by OpenSSL in Web Cryptography API? If the answers is yes. Great! You are going to find out. NOTE: This process can also be used for public key, you only need to change prefix and suffix to: -----BEGIN PUBLIC KEY----- ...

As from version 5.4, PHP comes with built-in server. It can be used to run application without need to install other http server like nginx or apache. Built-in server is designed only in controller environment for development and testing purposes. It can be run with command php -S : To test it cr...

C99 Since C99, C has variable length arrays, VLA, that model arrays with bounds that are only known at initialization time. While you have to be careful not to allocate too large VLA (they might smash your stack), using pointers to VLA and using them in sizeof expressions is fine. double sumAll(si...

We can declare a series of expressions in the REPL like this: Prelude> let x = 5 Prelude> let y = 2 * 5 + x Prelude> let result = y * 10 Prelude> x 5 Prelude> y 15 Prelude> result 150 To declare the same values in a file we write the following: -- demo.hs module De...

Suppose we have an array of integers and we want to figure out the maximum value without holding the whole array in memory all at once. This approach can be adapted to handle a variety of other situations in which data needs to be processed while being deserialized instead of after. extern crate se...

Do not allocate new objects in onDraw @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint paint = new Paint(); //Do not allocate here } Instead of drawing drawables in canvas... drawable.setBounds(boundsRect); drawable.draw(canvas); Use a B...

img{ float:left; width:100px; margin:0 10px; } .div1{ background:#f1f1f1; /* does not create block formatting context */ } .div2{ background:#f1f1f1; overflow:hidden; /* creates block formatting context */ } https://jsfiddle.net/MadalinaTn/qkwwmu6m/2/ Using the o...

git clean -f Will remove all untracked files.

Introduction Play has several plugins for different IDE-s. The eclipse plugin allows to transform a Play application into a working eclipse project with the command activator eclipse. Eclipse plugin may be set per project or globally per sbt user. It depends on team work, which approach should be u...

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