Tutorial by Examples: e

The Bridge pattern is one of the most basic Inversion of Control design patterns. For Xamarin, this pattern is used to reference platform-dependent code from a platform-independent context. For example: using Android's AlertDialog from a Portable Class Library or Xamarin Forms. Neither of those cont...
The Service Locator design pattern is very nearly dependency injection. Like the Bridge Pattern, this pattern can be used to reference platform-dependent code from a platform-independent context. Most interestingly, this pattern relies on the singleton pattern -- everything you put into the service ...
PSR-5 proposes a form of Generics-style notation for collections. Generics Syntax Type[] Type<Type> Type<Type[, Type]...> Type<Type[|Type]...> Values in a Collection MAY even be another array and even another Collection. Type<Type<Type>> Type<Type<Type[,...
To create a tooltip, we only need to add data-toggle="tooltip" attribute and a title to the HTML element that will have the tooltip. Title attribute is used to specify the text that is displayed inside the tooltip. <span data-toggle="tooltip" title="Hello world!"&gt...
Mediator pattern defines an object (Mediator) that encapsulates how a set of objects interact. It enables many-to-many communication. UML diagram: Key components: Mediator: Defines an interface for communication between Colleagues. Colleague: Is an abstract class, which defines the events to b...
The Monostate pattern is usually referred to as syntactic sugar over the Singleton pattern or as a conceptual Singleton. It avoids all the complications of having a single instance of a class, but all the instances use the same data. This is accomplished mostly by using static data members. One o...
In contrasto to the Singleton, the Monostate is suitable to be inherited to extend its functionalities, as long as member methods are not static. It follows a minimal example in C++: struct Settings { virtual std::size_t width() const noexcept { return width_; } virtual std::size_t heigh...
When only a single argument is supplied to numpy's where function it returns the indices of the input array (the condition) that evaluate as true (same behaviour as numpy.nonzero). This can be used to extract the indices of an array that satisfy a given condition. import numpy as np a = np.arang...
import unittest def addition(*args): """ add two or more summands and return the sum """ if len(args) < 2: raise ValueError, 'at least two summands are needed' for ii in args: if not isinstance(ii, (int, long, float, compl...
Installation npm install forever -g cd /node/project/directory Usages forever start app.js
SOAP is an acronym for Simple Object Access Protocol which defines a protocol that is used to exchange data via a Remote Procedure Call (RPC) with other SOAP services or clients. It is available in two version: SOAP 1.1 [IETF] SOAP 1.2 [IETF] SOAP 1.2 obsoletes SOAP 1.1 it is therefore recomm...
1. Logs: By default, Heroku allows only 1500 lines of consolidated logs. When more than 1500 lines of logs are required, one has to use addons provided Heroku. 2. Router: HTTP request have 30s timeout for initial response and 55s timeout thereafter. Maximum of 1MB buffer allowed for response. 3....
To use the value stored in a variable, use the dollar sign followed by the variable name enclosed by parentheses or curly braces. x = hello y = $(x) # y now contains the value "hello" y = ${x} # parentheses and curly braces are treated exactly the same If a variable's name is only ...
Simply-expanded variables behave like variables from traditional programming languages. The expression on the right-hand side is evaluated, and the result is stored in the variable. If the right-hand side contains a variable reference, that variable is expanded before the assignment takes place. ...
When defining a recursively-expanded variable, the contents of the right-hand side are stored as-is. If a variable reference is present, the reference itself is stored (not the value of the variable). Make waits to expand the variable references until the variable is actually used. x = hello y =...
Within the context of an individual rule, Make automatically defines a number of special variables. These variables can have a different value for each rule in a makefile and are designed to make writing rules simpler. These variables can only be used in the recipe portion of a rule. VariableDesc...
The ?= operator is an extension that behaves like =, except that the assignment only occurs if the variable is not already set. x = hello x ?= world # $(x) will yield "hello"
The += operator is a common extension that adds the specified content to the end of the variable, separated by a space. x = hello x += world Variable references in the right-hand side will be expanded if and only if the original variable was defined as a simply-expanded variable.
Helpers and fakeApplication Class Helpers is used a lot for unit tests. It imitates a Play application, fakes HTTP requests and responses, session, cookies - all whatever may be needed for tests. A controller under the test should be executed in a context of a Play application. The Helpers method f...
This is such a common requirement in iOS development, and it was always something that had to be done purely in code (or using images - yuck!). Now it's incredibly easy to preview his kind of thing in Interface Builder, there's absolutely no excuse for not using it. Here's the code:- import UIKit ...

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