Composability is Crucial

In all technical work, I find there is an often overlooked principal which delivers a huge amount of value: Composablity.

In OO programming, this is represented by the core ideas of “loose coupling” and “highly-cohesion”. These principles drive us towards creating objects which can be reused and transposed easily- basically, we aim to make our objects composable in different circumstances.

In scripting and the whole-program level, composabily takes many forms. Adding lots of import/export options to your software enable users to involve it in their work more easily, but things really get interesting when you look at composability taken seriously.

One of the driving ideas for Unix/Linux was that of “small, sharp tools”, programs which do one job, very well. The result is almost magical: once you have learned a handful of the hundreds of commands, you can start piping the output of one into another. Suddenly you have a sort of “data manipulation Lego”- once you find the piece you are looking for, you can add it on to your others and quickly get some advanced behaviour.

Whatever I am building, I keep thinking about how my choices will affect it’s composability and found it a very useful tool. Hopefully it’s an idea that might help others too!

Edit: Sandi Metz gave a great talk which highlights the use of composition/collaboration to avoid an “Omega problems” and keep your projects fun to work on.