It covers many subjects that other PHP books shy away from and provides really world examples. As only 10% of the material is PHP5 specific it's also useful for PHP4 users. It's not really a 'this is how you do suchathing in PHP' but more a concepts and ideas book with solid example code to back them up.
Here's a chapter summary.
- Part 1: Code Management
- Chapter 1: Coding Styles
- Chapter 2: Advanced Features
- Chapter 3: Error Checking/Handling
- Chapter 4: Implementing with PHP: Templates and the Web
- Chapter 5: Implementing with PHP: Standalone Scripts
- Chapter 6: Unit testing
- Part 2: Application Performance By Design
- Chapter 7: Managing Your Development Environment
- Chapter 8: Designing a Good API
- Chapter 9: External Performance Tunings
- Chapter 10: Data component caching
- Chapter 11: Computational Reuse
- Chapter 12: Interacting with Databases
- Part 3: Building Distributed Applications
- Chapter 13: User Authentication and Session Security
- Chapter 14: Session Handling
- Chapter 15: Building a distributed environment
- Chapter 16: RPC – Interacting with remote services
- Part 4: Performance
- Chapter 17: Application Benchmarks: Testing an entire application
- Chapter 18: Profiling
- Chapter 19: Synthetic Benchmarks: Evaluating code blocks and functions
- Chapter 20: PHP and Zend Engine Internals
- Chapter 21: Extending PHP Part 1
- Chapter 22: Extending PHP Part 2
- Chapter 23: Writing SAPIs and Extending the Zend Engine
