tag
design patterns
- #4 5 min
Proxies: Why They’re Useful and How They’re Implemented
I wanted to write about lazy loading, but doing so requires some background on proxies. Proxies are such an interesting and useful concept that I decided it would be worthwhile to write a separate post discussing them. I’ve talked about them in the past, for instance on StackOverflow, so this will be a bit of a rehash, but I will go into a little more depth here. What is a proxy? Fundamentally, it’s a broker, or mediator, between an object and that object’s user, which I will refer to as its client. Specifically, a proxy intercepts calls to the object, performs some logic, and then (typically) passes the call on to the object itself. I say typically because the proxy could simply intercept without ever calling the object.
- #1 8 min
Solving the Referential Integrity Problem
“A man with a watch knows what time it is. A man with two watches is never sure.” I’ve been developing my open source Android framework, Infinitum, for the better part of 10 months now. It has brought about some really interesting problems that I’ve had to tackle, which is one of the many reasons I enjoy working on it so much. Chicken or the Egg Although it’s much more now, Infinitum began as an object-relational mapper which was loosely modeled after Hibernate. One of the first major issues I faced while developing the ORM component was loading object graphs. To illustrate what I mean by this, suppose we’re developing some software for a department store. The domain model for this software might look something like this: