Question

I’m in the process of writing a DI framework for PHP 5, and I’ve been trying to find the ‘official’ definitions of some words in relation to dependency injection. Some of these words are ‘context‘ and ‘lifecycle‘. And also, what would I call the object that gets created/injected? Finally, what is the difference between components and services, and which term (if either) should I call the objects that can be injected?

I’ve read Martin Fowler’s article and looked through other DI frameworks (Phemto, Spring, Google Guice, Xyster, etc.), but I want to know what you think. Thanks!

Answer 1

Dependency Injection (DI) in computer programming refers to the process of supplying an external dependency to a software component. It is a specific form of inversion of control where the concern being inverted is the process of obtaining the needed dependency.

• lifecycle : singleton, per-request, transient …. how long should live in container
• components : A simpler definition can be: A component is an object written to a specification. It does not matter what the specification is: COM, Enterprise JavaBeans, etc., as long as the object adheres to the specification.
• services : The term service refers to a discretely defined set of contiguous and autonomous business or technical functionality.
• context : the separation at the container level of the provided implementations to the consumers. Example is the that golden partners on green pages will have 15% discount for red socks.

have fun 🙂