What is Inversion of Control?

What is Inversion of Control?

Inversion of Control (IoC) and Dependency Injection (DI) are two related practices in software development which are known to lead to higher testability and maintainability of software products. these patterns are said to be based on a principle, which states: "don't call us, we'll call you".

If you follow these simple two steps, you have done inversion of control:
  1. Separate what-to-do part from when-to-do part.
  2. Ensure that when part knows as little as possible about what part; and vice versa.
There are several techniques possible for each of these steps based on the technology/language you are using for your implementation.The inversion part of the Inversion of Control (IoC) is the confusing thing; because inversion is the relative term. The best way to understand IoC is to forget about that word!

Inversion of control is a practical way to reduce code duplication, and if you find yourself copying an entire method and only changing a small piece of the code, you can consider tackling it with inversion of control. Inversion of control is made easy in many languages through the concept of delegates, interfaces, or even raw function pointers.

Examples
  • Event Handling. Event Handlers (what-to-do part) while Raising Events (when-to-do part)
  • Interfaces. Component client - an interface (when-to-do part) while Component Interface implementation (what-to-do part)
  • Template method design pattern. template method when-to-do part -- primitive subclass implementation what-to-do part

Comments

Post a Comment

Popular posts from this blog

Data Bound Controls in ASP.Net - Part 4 (FormView and DetailsView controls)

FormView The FormView control is used to display a single record from a data source. It is similar to the DetailsView control, except it displays user-defined templates instead of row fields. Creating your own templates gives you greater flexibility in controlling how the data is displayed. The FormView control supports the following features: ·          Binding to data source controls, such as SqlDataSource and ObjectDataSource. ·          Built-in inserting, updating and deleting capabilities. ·          Built-in paging capabilities. ·          Programmatic access to the FormView object model to dynamically set properties, handle events, and so on. ·          Customizable appearance through user-defined templates, themes, and styles. Templates For the FormView control ...
Read more

JavaScript - ES2015 (aka ES6)

The ES2015 Since this long time passed between ES5.1 and ES6, the release is full of important new features and major changes in suggested best practices in developing JavaScript programs. To understand how fundamental ES2015 is, just keep in mind that with this version, the specification document went from 250 pages to ~600. In this blog, we describe the most important changes. Arrow Functions A new  this   scope Promises Generators let   and  const Classes Constructor Super Getters and setters Modules Importing modules Exporting modules Template Literals Default parameters The spread operator Destructuring assignments Enhanced Object Literals Simpler syntax to include variables Prototype super() Dynamic properties For-of loop Map and Set New String methods New Object methods Arrow functions Arrow functions since their introduction changed how most JavaScript code looks (and works). Visually, it’s a simple and welcome ...
Read more

The Clickjacking attack and X-Frame-Options

Clickjacking  Clickjacking is a type of “web framing” or “UI redressing” attack. What that simply means in practice is that: 1. A user (victim) is shown an innocuous, but enticing web page (think watch online video) 2. Another web page (that generally does something important – think add friends on social network) is layered on top of the first page and set to be transparent 3. When the user thinks they are clicking on the web page they see (video), they are actually clicking on the higher layered (framed) page that is transparent There are two main ways to prevent clickjacking: 1.     Sending the proper X-Frame-Options HTTP response headers that instruct the browser to not allow framing from other domains 2.     Employing defensive code in the UI to ensure that the current frame is the most top level window Using X-Frame-Options X-Frame-Options  originally invented by Microsoft for IE8, but supported by a number ...
Read more