Friday, 9 March 2007

Article: Validate User Input with the Strategy Pattern

In the final article of a two part series, Alejandro Gervasio show you how to implement the strategy pattern to check a wide range of user inputs. He says, this series walks you through the key points of how the strategy pattern works, and accompanies its theoretical concepts with hands-on examples.

In the first part of the article, he explained the foundations of the strategy design pattern, and complemented the theory with some practical examples of how to apply this pattern in PHP 5.

In the final tutorial, he demonstrates how to use the strategy pattern in a case of validating user-supplied input.

He explains the tutorial in the following sections:

• Building a validation strategy selector: he demonstrates how the strategy pattern can help to create a data validation system capable of verifying different types of user data.
• Building some strategy class: here he lists the respective signatures corresponding to these strategy classes.
• Validating user-supplied data: in this section he codes a short script that shows some illustrative cases where the validation strategy selector verifies firstly alphabetic and alphanumeric values, and lastly numbers and email addresses.
• Listing all the classes required to implement the strategy pattern : this section covers all the classes that he builds over the course of this tutorial to apply the strategy pattern with PHP 5