Tutorial by Examples: b

Block Indentation

Python uses indentation to define control and loop constructs. This contributes to Python's readability, however, it requires the programmer to pay close attention to the use of whitespace. Thus, editor miscalibration could result in code that behaves in unexpected ways. Python uses the colon symbo...

Python Language • Getting started with Python Language

Send text, key pressed and touch events to Android Device via ADB

execute the following command to insert the text into a view with a focus (if it supports text input) 6.0 Send text on SDK 23+ adb shell "input keyboard text 'Paste text on Android Device'" If already connected to your device via adb: input text 'Paste text on Android Device' 6...

Android • adb shell

Push a specific object to a remote branch

General syntax git push <remotename> <object>:<remotebranchname> Example git push origin master:wip-yourname Will push your master branch to the wip-yourname branch of origin (most of the time, the repository you cloned from). Delete remote branch Deleting the remote br...

Git • Pushing

Infinity and NaN ("not a number")

In all versions of Python, we can represent infinity and NaN ("not a number") as follows: pos_inf = float('inf') # positive infinity neg_inf = float('-inf') # negative infinity not_a_num = float('nan') # NaN ("not a number") In Python 3.5 and higher, we can also us...

Python Language • Math Module

Attributes

Mustaches can also be used inside HTML attributes: <div id="item-{{ id }}"></div> Note that attribute interpolations are disallowed in Vue.js directives and special attributes. Don’t worry, Vue.js will raise warnings for you when mustaches are used in wrong places.

Vue.js • Data Binding

Basic syntax

TypeScript is a typed superset of JavaScript, which means that all JavaScript code is valid TypeScript code. TypeScript adds a lot of new features on top of that. TypeScript makes JavaScript more like a strongly-typed, object-oriented language akin to C# and Java. This means that TypeScript code te...

TypeScript • Getting started with TypeScript

Basics

In Python 3 str is the type for unicode-enabled strings, while bytes is the type for sequences of raw bytes. type("f") == type(u"f") # True, <class 'str'> type(b"f") # <class 'bytes'> In Python 2 a casual string was a sequence of raw byte...

Python Language • Unicode and bytes

Class Based Views

Class based views let you focus on what make your views special. A static about page might have nothing special, except the template used. Use a TemplateView! All you have to do is set a template name. Job done. Next. views.py from django.views.generic import TemplateView class AboutView(Tem...

Django • Class based views

Form and object creation

Writing a view to create object can be quite boring. You have to display a form, you have to validate it, you have to save the item or return the form with an error. Unless you use one of the generic editing views. app/views.py from django.core.urlresolvers import reverse_lazy from django.views.g...

Django • Class based views

Basic Class Template

The basic idea of a class template is that the template parameter gets substituted by a type at compile time. The result is that the same class can be reused for multiple types. The user specifies which type will be used when a variable of the class is declared. Three examples of this are shown in m...

C++ • Templates

Using a context processor to access your most recent blog entries in all templates

Assuming you have a model called Post defined in your models.py file that contains blog posts, and has a date_published field. Step 1: Write the context processor Create (or add to) a file in your app directory called context_processors.py: from myapp.models import Post def recent_blog_posts...

Django • Context Processors

Speeding tough-to-vectorize for loops by byte compiling

Following the Rcpp example in this documentation entry, consider the following tough-to-vectorize function, which creates a vector of length len where the first element is specified (first) and each element x_i is equal to cos(x_{i-1} + 1): repeatedCosPlusOne <- function(first, len) { x <-...

R Language • Speeding up tough-to-vectorize code

Basic Django DB queries

Django ORM is a powerful abstraction that lets you store and retrieve data from the database without writing sql queries yourself. Let's assume the following models: class Author(models.Model): name = models.CharField(max_length=50) class Book(models.Model): name = models.CharField(max...

Django • Models

jQuery UI Sortable - Drop Placeholder

This example of the Sortable using a Placeholder is common usage. Sortable is applied to a group of DOM elements, allowing the user to move items around in the list via Drag'n Drop style actions. <!doctype html> <html lang="en"> <head> <meta charset="utf-8&q...

jQuery UI Library • jquery ui sortable

A basic unmanaged table.

At some point in your use of Django, you may find yourself wanting to interact with tables which have already been created, or with database views. In these cases, you would not want Django to manage the tables through its migrations. To set this up, you need to add only one variable to your model's...

Django • Models

Background Position

The background-position property is used to specify the starting position for a background image or gradient .myClass { background-image: url('path/to/image.jpg'); background-position: 50% 50%; } The position is set using an X and Y co-ordinate and be set using any of the units used withi...

CSS • Backgrounds

Basic Test

main.go: package main import ( "fmt" ) func main() { fmt.Println(Sum(4,5)) } func Sum(a, b int) int { return a + b } main_test.go: package main import ( "testing" ) // Test methods start with `Test` func TestSum(t *testing.T) { go...

Go • Testing

Benchmark tests

If you want to measure benchmarks add a testing method like this: sum.go: package sum // Sum calculates the sum of two integers func Sum(a, b int) int { return a + b } sum_test.go: package sum import "testing" func BenchmarkSum(b *testing.B) { for i := 0; i < ...

Go • Testing

Table-driven unit tests

This type of testing is popular technique for testing with predefined input and output values. Create a file called main.go with content: package main import ( "fmt" ) func main() { fmt.Println(Sum(4, 5)) } func Sum(a, b int) int { return a + b } After you r...

Go • Testing

Basic selectors

SelectorDescription*Universal selector (all elements)divTag selector (all <div> elements).blueClass selector (all elements with class blue).blue.redAll elements with class blue and red (a type of Compound selector)#headlineID selector (the element with "id" attribute set to headline)...

CSS • Selectors