Tutorial by Examples: s

First, download the compiler and components. Next, add Swift to your path. On macOS, the default location for the downloadable toolchain is /Library/Developer/Toolchains. Run the following command in Terminal: export PATH=/Library/Developer/Toolchains/swift-latest.xctoolchain/usr/bin:"${PATH}...

Technically, autoloading works by executing a callback when a PHP class is required but not found. Such callbacks usually attempt to load these classes. Generally, autoloading can be understood as the attempt to load PHP files (especially PHP class files, where a PHP source file is dedicated for a ...

An anonymous function is just a function that doesn't have a name. // Anonymous function function() { return "Hello World!"; }; In PHP, an anonymous function is treated like an expression and for this reason, it should be ended with a semicolon ;. An anonymous function should b...

In PHP, an anonymous function has its own scope like any other PHP function. In JavaScript, an anonymous function can access a variable in outside scope. But in PHP, this is not permitted. $name = 'John'; // Anonymous function trying access outside scope $sayHello = function() { return &q...

A closure is an anonymous function that can't access outside scope. When defining an anonymous function as such, you're creating a "namespace" for that function. It currently only has access to that namespace. $externalVariable = "Hello"; $secondExternalVariable = "Foo&qu...

A std::vector can be useful for returning a dynamic number of variables of the same type. The following example uses int as data type, but a std::vector can hold any type that is trivially copyable: #include <vector> #include <iostream> // the following function returns all integers...

Program units often make use of literal constants. These cover the obvious cases like print *, "Hello", 1, 1.0 Except in one case, each literal constant is a scalar which has type, type parameters and value given by the syntax. Integer literal constants are of the form 1 -1 -1_1 ...

You can call a function in Racket by wrapping it in parentheses with the arguments after it. This looks like (function argument ...). > (define (f x) x) > (f 1) 1 > (f "salmon") "salmon" > (define (g x y) (string-append x y)) > (g "large" "sal...

The 0b prefix can be used to represent Binary literals. Binary literals allow constructing numbers from zeroes and ones, which makes seeing which bits are set in the binary representation of a number much easier. This can be useful for working with binary flags. The following are equivalent ways o...

The underscore _ may be used as a digit separator. Being able to group digits in large numeric literals has a significant impact on readability. The underscore may occur anywhere in a numeric literal except as noted below. Different groupings may make sense in different scenarios or with different ...

Basics A tuple is an ordered, finite list of elements. Tuples are commonly used in programming as a means to work with one single entity collectively instead of individually working with each of the tuple's elements, and to represent individual rows (ie. "records") in a relational databa...

Local functions are defined within a method and aren't available outside of it. They have access to all local variables and support iterators, async/await and lambda syntax. This way, repetitions specific to a function can be functionalized without crowding the class. As a side effect, this improves...

Define AccumulatorParam import org.apache.spark.AccumulatorParam object StringAccumulator extends AccumulatorParam[String] { def zero(s: String): String = s def addInPlace(s1: String, s2: String)= s1 + s2 } Use: val accumulator = sc.accumulator("")(StringAccumulator) sc.pa...

Define AccumulatorParam: from pyspark import AccumulatorParam class StringAccumulator(AccumulatorParam): def zero(self, s): return s def addInPlace(self, s1, s2): return s1 + s2 accumulator = sc.accumulator("", StringAccumulator()) def add(x): gl...

Preconditions allows methods to provide minimum required values for input parameters Example... void DoWork(string input) { Contract.Requires(!string.IsNullOrEmpty(input)); //do work } Static Analysis Result...

Postconditions ensure that the returned results from a method will match the provided definition. This provides the caller with a definition of the expected result. Postconditions may allowed for simplied implmentations as some possible outcomes can be provided by the static analyizer. Example......

AlertDialog.Builder builder = new AlertDialog.Builder(context); //Set Title builder.setTitle("Reset...") //Set Message .setMessage("Are you sure?") //Set the icon of the dialog .setIcon(drawable) //Set...

Let there be Activity B that can be opened, and can further start more Activities. But, user should not encounter it when navigating back in task activities. The simplest solution is to set the attribute noHistory to true for that <activity> tag in AndroidManifest.xml: <activity a...

Imagine you have the following HTML: <div> <label>Name:</label> John Smith </div> And you need to locate the text "John Smith" after the label element. In this case, you can locate the label element by text and then use .next_sibling property: from ...

BeautifulSoup has a limited support for CSS selectors, but covers most commonly used ones. Use select() method to find multiple elements and select_one() to find a single element. Basic example: from bs4 import BeautifulSoup data = """ <ul> <li class="item&quo...