m0smithslash's Journal: Software Development - Feb 2004, Vol 12, No. 2

It's the Crosscutting

Explains some of the terms used in Aspect Oriented Programming

• concern - An element of a program that can be considered a single unit; think module
• separation of concerns - placing each concern by itself; think module
• scattered - not modularized
• structures - how your concerns are organized

These ideas apply outside AOP. For example, if there is a constant, say number of minutes in an hour that is being used in a lot of places. If you use 60 everywhere, then this "concern" ( number is minutes in an hour ) is scattered. If you define a single global constant, MINUTES_PER_HOUR, in a single place and use it instead then it is called "modularized". By putting all such contstants in the same package, you impose structure.

There are concerns that can't be separated nicely from other concerns. These concerns crosscut the structure. Example: system kernel calls. Cross cutting allows for multiple simultaneous structures, rather than a single hierarchy as we are all used to.

You will need to understand koan