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Variables are annotated using comments: x = 3 # type: int x = negate(x) x = 'a type-checker might catch this error' Python 3.x3.6 Starting from Python 3.6, there is also new syntax for variable annotations. The code above might use the form x: int = 3 Unlike with comments, it is also pos...

Double quoteSingle quoteAllows variable expansionPrevents variable expansionAllows history expansion if enabledPrevents history expansionAllows command substitutionPrevents command substitution* and @ can have special meaning* and @ are always literalsCan contain both single quote or double quoteSin...

One way to mock a function is to use the create_autospec function, which will mock out an object according to its specs. With functions, we can use this to ensure that they are called appropriately. With a function multiply in custom_math.py: def multiply(a, b): return a * b And a function...

You can force deallocate objects even if their refcount isn't 0 in both Python 2 and 3. Both versions use the ctypes module to do so. WARNING: doing this will leave your Python environment unstable and prone to crashing without a traceback! Using this method could also introduce security problems ...

Create User Model rails generate model User email:string password_digest:string Add has_secure_password module to User model class User < ActiveRecord::Base has_secure_password end Now you can create a new user with password user = User.new email: '[email protected]', password: 'Password1', ...

To play audio using the Web Audio API, we need to get an ArrayBuffer of audio data and pass it to a BufferSource for playback. To get an audio buffer of the sound to play, you need to use the AudioContext.decodeAudioData method like so: const audioCtx = new (window.AudioContext || window.webkitAud...

User Prompts are methods part of the Web Application API used to invoke Browser modals requesting a user action such as confirmation or input. window.alert(message) Show a modal popup with a message to the user. Requires the user to click [OK] to dismiss. alert("Hello World"); More...

When using prompt a user can always click Cancel and no value will be returned. To prevent empty values and make it more persistent: <h2>Welcome <span id="name"></span>!</h2> <script> // Persistent Prompt modal var userName; while(!userName) { userN...

Using the dataset property The new dataset property allows access (for both reading and writing) to all data attributes data-* on any element. <p>Countries:</p> <ul> <li id="C1" onclick="showDetails(this)" data-id="US" data-dial-code="1&q...

The code below will prompt for numbers and continue to add them to the beginning of a linked list. /* This program will demonstrate inserting a node at the beginning of a linked list */ #include <stdio.h> #include <stdlib.h> struct Node { int data; struct Node* next; }; ...

A JSON Array is an ordered collection of values. It is surrounded by square braces i.e [], and values are comma-delimited: { "colors" : [ "red", "green", "blue" ] } JSON Arrays can also contain any valid JSON element, including objects, as in this example ...

This way may seem to be uselss becuase you are using anonymous function to acomplish something that you can do it with join(); But if you need to make something to the strings while you are converting the Array to String, this can be useful. var arr = ['a', 'á', 'b', 'c'] function upper_lower (...

This example shows how to use two audio sources, and alter one of them based on the other. In this case we create an audio Ducker, that will lower the volume of the primary track if the secondary track produces sound. The ScriptProcessorNode will send regular events to its audioprocess handler. In ...

Matrix multiplication can be done in two equivalent ways with the dot function. One way is to use the dot member function of numpy.ndarray. >>> import numpy as np >>> A = np.ones((4,4)) >>> A array([[ 1., 1., 1., 1.], [ 1., 1., 1., 1.], [ 1., 1.,...

The numpy dot function has an optional parameter out=None. This parameter allows you to specify an array to write the result to. This array must be exactly the same shape and type as the array that would have been returned, or an exception will be thrown. >>> I = np.eye(2) >>> I ...

Since functions are ordinary values, there is a convenient syntax for creating functions without names: List.map (fun x -> x * x) [1; 2; 3; 4] (* - : int list = [1; 4; 9; 16] *) This is handy, as we would otherwise have to name the function first (see let) to be able to use it: let square x...

class Plane { enum Emergency: ErrorType { case NoFuel case EngineFailure(reason: String) case DamagedWing } var fuelInKilograms: Int //... init and other methods not shown func fly() throws { // ... if fuelInKilograms ...

const int a = 0; /* This variable is "unmodifiable", the compiler should throw an error when this variable is changed */ int b = 0; /* This variable is modifiable */ b += 10; /* Changes the value of 'b' */ a += 10; /* Throws a compiler error */ The const qualif...

If while working you realize you're on wrong branch and you haven't created any commits yet, you can easily move your work to correct branch using stashing: git stash git checkout correct-branch git stash pop Remember git stash pop will apply the last stash and delete it from the stash list. T...

process.argv is an array containing the command line arguments. The first element will be node, the second element will be the name of the JavaScript file. The next elements will be any additional command line arguments. Code Example: Output sum of all command line arguments index.js var sum = 0...