Tutorial by Examples: co

In most scripting languages, if a function call fails, it may throw an exception and stop execution of the program. Bash commands do not have exceptions, but they do have exit codes. A non-zero exit code signals failure, however, a non-zero exit code will not stop execution of the program. This can...

The behaviour of virtual functions in constructors and destructors is often confusing when first encountered. #include <iostream> using namespace std; class base { public: base() { f("base constructor"); } ~base() { f("base destructor"); } virtual co...

Principal Component Analysis finds sequences of linear combinations of the features. The first linear combination maximizes the variance of the features (subject to a unit constraint). Each of the following linear combinations maximizes the variance of the features in the subspace orthogonal to that...

public class Producer { private static Random random = new Random((int)DateTime.UtcNow.Ticks); //produce the value that will be posted to buffer block public double Produce ( ) { var value = random.NextDouble(); Console.WriteLine($"Producing value: {value}...

The auto keyword by itself represents a value type, similar to int or char. It can be modified with the const keyword and the & symbol to represent a const type or a reference type, respectively. These modifiers can be combined. In this example, s is a value type (its type will be inferred as s...

SoundEffect.Play() plays the sound effect in a "fire-and-forget" fashion. The sound plays once and its lifetime is managed by the framework. You are not able to change the properties (volume, pan, pitch) of the sound during playback, loop it, position it in 3D or pause it. You can hold a ...

This is a relatively common mistake: You created an rect element, in a bar chart for instance, and you want to add a text label (let's say, the value of that bar). So, using the same variable that you used to append the rect and define its x and y position, you append your text element. Very logic, ...

Arrow is, vaguely speaking, the class of morphisms that compose like functions, with both serial composition and “parallel composition”. While it is most interesting as a generalisation of functions, the Arrow (->) instance itself is already quite useful. For instance, the following function: sp...

Set a convenience method in your base model namespace Base; class Model extends \Phalcon\Mvc\Model { public function sanitize($attr, $filterName) { $filter = $this->getDI()->get('filter'); $this->$attr = $filter->sanitize($this->$attr, $filterName); ...

Explanation In this example a simple Trigger has been created to change the Close Date of an Opportunity, that's about to be inserted or updated, to a date 10 days in the future. The Apex Controller custom setting's checkbox field enables the code to be disabled at the user / profile / org level. ...

Sometimes we need to accept route params as well as access the HTTP Request params. We can still type hint the Requests class in laravel controller and achieve that as explained below E.g. We have a route that update a certain post like this (passing post id i route ) Route::put('post/{id}', 'Post...

In C, multi-line comments, /* and */, do not nest. If you annotate a block of code or function using this style of comment: /* * max(): Finds the largest integer in an array and returns it. * If the array length is less than 1, the result is undefined. * arr: The array of integers to search....

Resolving scoped services during application startup can be difficult, because there is no request and hence no scoped service. Resolving a scoped service during application startup via app.ApplicationServices.GetService<AppDbContext>() can cause issues, because it will be created in the sc...

Various websites provide online access to C++ compilers. Online compiler's feature set vary significantly from site to site, but usually they allow to do the following: Paste your code into a web form in the browser. Select some compiler options and compile the code. Collect compiler and/or pro...

functions.php: function rm_init_js() { wp_enqueue_script( 'custom-ajax-script', get_template_directory_uri() . '/js/ajax.js', array( 'jquery', 'wp-util' ), '1.0', true ); // pass custom variables to JS wp_localize_script( 'custom-ajax-script', 'BEJS', array( 'action' => ...

If, during the conversion of: an integer type to a floating point type, a floating point type to an integer type, or a floating point type to a shorter floating point type, the source value is outside the range of values that can be represented in the destination type, the result is undefine...

When starting Zsh, it'll source the following files in this order by default: /etc/zsh/zshenv Used for setting system-wide environment variables; it should not contain commands that produce output or assume the shell is attached to a tty. This file will always be sourced, this cannot be overrid...

The "child" components of a component are available on a special prop, props.children. This prop is very useful for "Compositing" components together, and can make JSX markup more intuitive or reflective of the intended final structure of the DOM: var SomeComponent = function ...

Using git show we can view a single commit git show 48c83b3 git show 48c83b3690dfc7b0e622fd220f8f37c26a77c934 Example commit 48c83b3690dfc7b0e622fd220f8f37c26a77c934 Author: Matt Clark <[email protected]> Date: Wed May 4 18:26:40 2016 -0400 The commit message will be show...

You can use Modules to build more complex classes through composition. The include ModuleName directive incorporates a module's methods into a class. module Foo def foo_method puts 'foo_method called!' end end module Bar def bar_method puts 'bar_method called!' end end ...