Tutorial by Examples: en

As Go uses implicit interface implementation, you will not get a compile-time error if your struct does not implement an interface you had intended to implement. You can test the implementation explicitly using type casting: type MyInterface interface { Thing() } type MyImplementer struct {} ...

First it is important to understand that the Core Data Model is the *.xcdatamodeld file. You will notice you have not entities. You will have to create one yourself. At the bottom of Xcode you will notice a button that says "Add Entity" click it and you will have a new entity in the ...

Under the attributes section you add the attributes to your model. This button is a plus located at the bottom of the section. You can add any attributes that are relevant to your app. You have several options of types to choose from ranging from Booleans to Dates and more. The Inspector panel also ...

The map operation is a useful tool when working with arrays and vectors, but it can also be used to deal with Option values in a functional way. fn main() { // We start with an Option value (Option<i32> in this case). let some_number = Some(9); // Let's do some consecutive ...

Exceptions in Laravel are handled by App\Exceptions\Handler.php This file contains two functions by default. Report & Render. We will only be using the first public function report(Exception $e) The report method is used to log exceptions or send them to an external service like BugSnag...

One common use for the FOR XML function is to concatenate the values of multiple rows. Here's an example using the Customers table: SELECT STUFF( (SELECT ';' + Email FROM Customers where (Email is not null and Email <> '') ORDER BY Email ASC FOR XM...

Sometimes we have to resize a UILabel based on dynamic content where the text length is unknown. In this example, width of the UILabel is fixed at 280 points and the height is infinite, lets say 9999. Estimating the frame with respect to the text style and maximumLabelSize. Objective-C UILabel * l...

Often times, responsive web design involves media queries, which are CSS blocks that are only executed if a condition is satisfied. This is useful for responsive web design because you can use media queries to specify different CSS styles for the mobile version of your website versus the desktop ver...

If you have a multi-parameter type-class with arguments a, b, c, and x, this extension lets you express that the type x can be uniquely identified from a, b, and c: class SomeClass a b c x | a b c -> x where ... When declaring an instance of such class, it will be checked against all other in...

HTML comments (optionally preceded by whitespace) will cause code (on the same line) to be ignored by the browser also, though this is considered bad practice. One-line comments with the HTML comment opening sequence (<!--): Note: the JavaScript interpreter ignores the closing characters of H...

When developing several applications on one machine, it becomes useful to separate out dependencies into virtual environments. With the use of virtualenv, these environments are sourced into your shell so that when you run a command, it comes from that virtual environment. This is most commonly in...

brew install open-mpi

There are situations when we don't want to rely upon Free Store for allocating memory and we want to use custom memory allocations using new. For these situations we can use Placement New, where we can tell `new' operator to allocate memory from a pre-allocated memory location For example int a4b...

Controlled form components are defined with a value property. The value of controlled inputs is managed by React, user inputs will not have any direct influence on the rendered input. Instead, a change to the value property needs to reflect this change. class Form extends React.Component { con...

Uncontrolled components are inputs that do not have a value property. In opposite to controlled components, it is the application's responsibility to keep the component state and the input value in sync. class Form extends React.Component { constructor(props) { super(props); th...

You can remove any of the conventions defined in the System.Data.Entity.ModelConfiguration.Conventions namespace, by overriding OnModelCreating method. The following example removes PluralizingTableNameConvention. public class EshopContext : DbContext { public DbSet<Product> Products...

for comprehensions in Scala are just syntactic sugar. These comprehensions are implemented using the withFilter, foreach, flatMap and map methods of their subject types. For this reason, only types that have these methods defined can be utilized in a for comprehension. A for comprehension of the fo...

Comparing string in a case insensitive way seems like something that's trivial, but it's not. This section only considers unicode strings (the default in Python 3). Note that Python 2 may have subtle weaknesses relative to Python 3 - the later's unicode handling is much more complete. The first thi...

.message color: white .message-important @extend .message background-color: red This will take all of the styles from .message and add them to .message-important. It generates the following CSS: .message, .message-important { color: white; } .message-important { background-...

.message color: white .important background-color: red .message-important @extend .message, .important In the above code @extend is used in one line to add multiple classes' code to .message-important, however, it is possible to use one extend per line like this: .message-importan...