Object Composition for Service Migration

Object Composition is a very powerful and pervasive software design technique. Yet, paradoxically, it is an underutilized design pattern whose lack of usage is the root of many anti-patterns in software development. One that I continue to come across regularly has to do with not using composition to test and migrate a piece of software from one service to another.

Briefly, Object Composition is combining two or more objects to create more complex objects while keeping definitions of the constituent objects unchanged (unlike inheritance, which extends these definitions)

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Scripts and their undo

TL;DR. Scripts are a great way to automate the mundane. But be sure you give yourself a way out — an undo — when running them.

Some time ago, I had to carry out a long sequence of manual changes in the deployment of my ‘cloud’ service, and so like a good software engineer, I automated large chunks of these changes with shell scripts. Here I learned the importance of building and ‘undo’ in all your shell scripts that mutate the state of world.

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