Tutorial by Examples: en

<?php if ($condition): do_something(); elseif ($another_condition): do_something_else(); else: do_something_different(); endif; ?> <?php if ($condition): ?> <p>Do something in HTML</p> <?php elseif ($another_condition): ?> <p>...

To change the default stack order positioned elements (position property set to relative, absolute or fixed), use the z-index property. The higher the z-index, the higher up in the stacking context (on the z-axis) it is placed. Example In the example below, a z-index value of 3 puts green on to...

Let's create our own error type for this example. 2.2 enum CustomError: ErrorType { case SomeError case AnotherError } func throwing() throws { throw CustomError.SomeError } 3.0 enum CustomError: Error { case someError case anotherError } func throwing() thr...

If you are using the default bash prompt on Linux, you should see the name of the virtual environment at the start of your prompt. (my-project-env) user@hostname:~$ which python /home/user/my-project-env/bin/python

In Rails, you find yourself looking at controllers, views, and models for your database. To reduce the need for heavy configuration, Rails implements rules to ease up working with the application. You may define your own rules but for the beginning (and for later on) it's a good idea to stick to co...

The default value for an enum is zero. If an enum does not define an item with a value of zero, its default value will be zero. public class Program { enum EnumExample { one = 1, two = 2 } public void Main() { var e =...

To generate a controller (for example Posts), navigate to your project directory from a command line or terminal, and run: $ rails generate controller Posts You can shorten this code by replacing generate with g, for example: $ rails g controller Posts If you open up the newly generated app/...

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...

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...

It is common to want two views to be side by side, centered in their superview. The common answer given on Stack Overflow is to embed these two views in a UIView and center the UIView. This is not necessary or recommended. From the UILayoutGuide docs: There are a number of costs associated with...

.encode and .decode both have error modes. The default is 'strict', which raises exceptions on error. Other modes are more forgiving. Encoding >>> "£13.55".encode('ascii', errors='replace') b'?13.55' >>> "£13.55".encode('ascii', errors='ignore') b'13.55' ...

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...

While the math.sqrt function is provided for the specific case of square roots, it's often convenient to use the exponentiation operator (**) with fractional exponents to perform nth-root operations, like cube roots. The inverse of an exponentiation is exponentiation by the exponent's reciprocal. S...

To demystify Template Haskell, suppose you have data Example a = Example { _foo :: Int, _bar :: a } then makeLenses 'Example produces (more or less) foo :: Lens' (Example a) Int bar :: Lens (Example a) (Example b) a b There's nothing particularly magical going on, though. You can write ...

A Lens' s a means that you can always find an a within any s. A Prism' s a means that you can sometimes find that s actually just is a but sometimes it's something else. To be more clear, we have _1 :: Lens' (a, b) a because any tuple always has a first element. We have _Just :: Prism' (Maybe a) a...

If you have a f :: Lens' a b and a g :: Lens' b c then f . g is a Lens' a c gotten by following f first and then g. Notably: Lenses compose as functions (really they just are functions) If you think of the view functionality of Lens, it seems like data flows "left to right"—this might ...

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...

Context processor to determine the template based on group membership(or any query/logic). This allows our public/regular users to get one template and our special group to get a different one. myapp/context_processors.py def template_selection(request): site_template = 'template_public.html...