Tutorial by Examples: the

Complex numbers and the cmath module

The cmath module is similar to the math module, but defines functions appropriately for the complex plane. First of all, complex numbers are a numeric type that is part of the Python language itself rather than being provided by a library class. Thus we don't need to import cmath for ordinary arith...

Invalidating the module cache

In development, you may find that using require() on the same module multiple times always returns the same module, even if you have made changes to that file. This is because modules are cached the first time they are loaded, and any subsequent module loads will load from the cache. To get around ...

Using Elements from the Polymer Catalog

Polymer prodives a lot of well built elements for you to use in your app. Browse them in their Element Catalog. Let's go through the workflow of using an element by including paper-input (Documentation) Download the Element To Download an element there are two ways: Bower The convinient way is...

Example showcasing the basic concepts

The following example is an introduction to: Template compilation using underscore Accessing variables in a template Creating a view Rendering a view Showing a view <html> <head> <script src="https://code.jquery.com/jquery-3.1.0.min.js"></script> ...

Unit testing using Theories

From JavaDoc The Theories runner allows to test a certain functionality against a subset of an infinite set of data points. Running theories import org.junit.experimental.theories.Theories; import org.junit.experimental.theories.Theory; import org.junit.runner.RunWith; @RunWith(Theories...
junit • Tests

Never Assume The Worksheet

Even when all your work is directed at a single worksheet, it's still a very good practice to explicitly specify the worksheet in your code. This habit makes it much easier to expand your code later, or to lift parts (or all) of a Sub or Function to be re-used someplace else. Many developers establi...

Using the sessions object within a view

First, ensure you have imported sessions from flask from flask import session To use session, a Flask application needs a defined SECRET_KEY. app = Flask(__name__) app.secret_key = 'app secret key' Sessions are implemented by default using a cookie signed with the secret key. This ensures t...

Listing all folders in the current directory

package main import ( "fmt" "io/ioutil" ) func main() { files, err := ioutil.ReadDir(".") if err != nil { panic(err) } fmt.Println("Folders in the current directory:") for _, fileInfo := range files { ...
Go • File I/O

Cloning the SVN repository

You need to create a new local copy of the repository with the command git svn clone SVN_REPO_ROOT_URL [DEST_FOLDER_PATH] -T TRUNK_REPO_PATH -t TAGS_REPO_PATH -b BRANCHES_REPO_PATH If your SVN repository follows the standard layout (trunk, branches, tags folders) you can save some typing: git svn...
Git • git-svn

Getting the latest changes from SVN

The equivalent to git pull is the command git svn rebase This retrieves all the changes from the SVN repository and applies them on top of your local commits in your current branch. You can also use the command git svn fetch to retrieve the changes from the SVN repository and bring them to ...
Git • git-svn

The recipe for an immutable class

An immutable object is an object whose state cannot be changed. An immutable class is a class whose instances are immutable by design, and implementation. The Java class which is most commonly presented as an example of immutability is java.lang.String. The following is a stereotypical example: ...

The worker model

# this method can be anything and anywhere as long as it is accessible for connection @pyqtSlot() def run_on_complete(): pass # An object containing methods you want to run in a thread class Worker(QObject): complete = pyqtSignal() @pyqtSlot() def a_method_to_run...

Getting the difference between two dates / times

The most feasible way is to use, the DateTime class. An example: <?php // Create a date time object, which has the value of ~ two years ago $twoYearsAgo = new DateTime("2014-01-18 20:05:56"); // Create a date time object, which has the value of ~ now $now = new DateTime("2016...

Using optionals to represent the absence of a value

Before C++17, having pointers with a value of nullptr commonly represented the absence of a value. This is a good solution for large objects that have been dynamically allocated and are already managed by pointers. However, this solution does not work well for small or primitive types such as int, w...

Using optionals to represent the failure of a function

Before C++17, a function typically represented failure in one of several ways: A null pointer was returned. e.g. Calling a function Delegate *App::get_delegate() on an App instance that did not have a delegate would return nullptr. This is a good solution for objects that have been dynamicall...

Creating A Custom Element Using the @customElement Decorator

In most examples, the class naming convention is used to define an Aurelia Custom Element. However, Aurelia also provides a decorator that can be used to decorate a class. The class is again treated as a custom element by Aurelia then. The value supplied to the decorator becomes the name of the cus...

Select the contents of an element

let sel = document.getSelection(); let myNode = document.getElementById('element-to-select'); let range = document.createRange(); range.selectNodeContents(myNode); sel.addRange(range); It may be necessary to first remove all the ranges of the previous selection, as most browsers don't s...

Get the text of the selection

let sel = document.getSelection(); let text = sel.toString(); console.log(text); // logs what the user selected Alternatively, since the toString member function is called automatically by some functions when converting the object to a string, you don't always have to call it yourself. console...

Using the function keyword

The function keyword automatically has pattern matching when you define the body of your function. Observe it below: # let foo = function 0 -> "zero" | 1 -> "one" | 2 -> "couple" | 3 -> "few" | _ -> "many";; val foo : int -&gt...

Remove all objects from the display list

If targeting Flash Player 11+, the built-in removeChildren method is the best way to remove all children: removeChildren(); //a start and end index can be passed For legacy applications, the same can be accomplished with a loop: while (numChildren > 0) { removeChildAt(0); }

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