Tutorial by Examples: st

You can create a tuple and use a switch like so: var str: String? = "hi" var x: Int? = 5 switch (str, x) { case (.Some,.Some): print("Both have values") case (.Some, nil): print("String has a value") case (nil, .Some): print("Int has a value&...

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...

Literal format strings were introduced in PEP 498 (Python3.6 and upwards), allowing you to prepend f to the beginning of a string literal to effectively apply .format to it with all variables in the current scope. >>> foo = 'bar' >>> f'Foo is {foo}' 'Foo is bar' This works wi...

This assumes that you have read the documentation about starting a new Django project. Let us assume that the main app in your project is named td (short for test driven). To create your first test, create a file named test_view.py and copy paste the following content into it. from django.test impo...

Detailed instructions on getting couchbase set up or installed.

Getting the Constructor Object You can obtain Constructor class from the Class object like this: Class myClass = ... // get a class object Constructor[] constructors = myClass.getConstructors(); Where the constructors variable will have one Constructor instance for each public constructor decl...

Many C interfaces such as SDL2 have their own deletion functions. This means that you cannot use smart pointers directly: std::unique_ptr<SDL_Surface> a; // won't work, UNSAFE! Instead, you need to define your own deleter. The examples here use the SDL_Surface structure which should be fre...

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...

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 < ...

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...

This type of tests make sure that your code compiles properly and will appear in the generated documentation for your project. In addition to that, the example tests can assert that your test produces proper output. sum.go: package sum // Sum calculates the sum of two integers func Sum(a, b in...

Here is a simple model that we will use to run a few test queries: class MyModel(models.Model): name = models.CharField(max_length=10) model_num = models.IntegerField() flag = models.NullBooleanField(default=False) Get a single model object where the id/pk is 4: (If there are no...

Create a new playground file: First option: From Xcode welcome screen, select the first option (Get started with a playground). Second option: From menu select File → New → Playground (⌥⇧⌘N). Name your playground and select the platform (iOS/macOS/tvOS), then click Next. ...

Using Playground it is easy to see that happens inside loops or objects while the change is happening. For example, in the code below, the value of x will change from 1 to 4. import UIKit for x in [1, 2, 3, 4] { x } (1) Clicking on the eye symbol on the right will give us a quick look. (2...

models.py : from __future__ import unicode_literals from django.db import models from django.contrib.auth.models import ( AbstractBaseUser, BaseUserManager, PermissionsMixin) from django.utils import timezone from django.utils.translation import ugettext_lazy as _ class UserManage...

The ls command's -S option sorts the files in descending order of file size. $ ls -l -S ./Fruits total 444 -rw-rw-rw- 1 root root 295303 Jul 28 19:19 apples.jpg -rw-rw-rw- 1 root root 102283 Jul 28 19:19 kiwis.jpg -rw-rw-rw- 1 root root 50197 Jul 28 19:19 bananas.jpg When used with the -r o...

The const keyword declares a global constant binding. const DEADBEEF: u64 = 0xDEADBEEF; fn main() { println("{:X}", DEADBEEF); } This outputs DEADBEEF

The static keyword declares a global static binding, which may be mutable. static HELLO_WORLD: &'static str = "Hello, world!"; fn main() { println("{}", HELLO_WORLD); } This outputs Hello, world!

This technique works even when the container's dimensions are unknown. Set up a "ghost" element inside the container to be centered that is 100% height, then use vertical-align: middle on both that and the element to be centered. CSS /* This parent can be any width and height */ .block...

In addition to reading data with Eloquent, you can also use it to insert or update data with the save() method. If you have created a new model instance then the record will be inserted; otherwise, if you have retrieved a model from the database and set new values, it will be updated. In this exa...