Notes for current slide

Press 'C' to clone and move it to projector
Press 'P' to show these here presenter notes

75 minutes

When you're mired in an ancient codebase that makes refactoring risky and expensive, how do you clear a path to continued delivery? According to the old saw, the best time to plant a tree is 20 years ago, and the next best time is today. But if you already have a gnarled old source tree, an old saw is the wrong tool. Instead, plant a Strangler: a pattern for preserving your software investment by arranging for new functionality to grow in a new codebase.

As a mob, we'll take a quick look at a Strangler, then test-drive new features into it. Don't know what to try next? Take the keyboard. Got an idea? Step away and talk someone else through it. You'll leave with a powerful strategy for extending the useful life of working, valuable software -- especially when it's hard to change. We'll also send you home with a free bonus development practice to accelerate your team's learning. For a limited time only!

How to introduce the problem

Responsible for production email service
Keep having to extend it (business, regulatory requirements)
Look at ofmipd code
On my 20% time, I had an idea for how to make development easier, cheaper, safer
Run ofmipd
Run ofmipd behind env AUTHUP_USER=tim fixsmtpio
Note the differences?
We're going to do the same kind of thing, in Python
Let's run it and say "WORD UP" to the server
See how that works
Okay, let's make a new test pass

Notes for next slide

@schmonz

#hackerkegeln

schmonz.com/talk
/2018-nuernberg

Strangle Your Legacy Code

Amitai Schleier

2018/07/12

1 / 12

Press 'C' to clone and move it to projector
Press 'P' to show these here presenter notes

75 minutes

How to introduce the problem

Responsible for production email service
Keep having to extend it (business, regulatory requirements)
Look at ofmipd code
On my 20% time, I had an idea for how to make development easier, cheaper, safer
Run ofmipd
Run ofmipd behind env AUTHUP_USER=tim fixsmtpio
Note the differences?
We're going to do the same kind of thing, in Python
Let's run it and say "WORD UP" to the server
See how that works
Okay, let's make a new test pass

@schmonz

#hackerkegeln

schmonz.com/talk
/2018-nuernberg

Goals For This Session

1. Introduction to Strangler

2. Develop in a real Strangler

3. Collect learnings

2 / 12

@schmonz

#hackerkegeln

schmonz.com/talk
/2018-nuernberg

0. Code of Conduct

softwerkskammer.org/wiki
/diversity/index

Remind ourselves how we want to behave

Like TDD, declaring our intentions helps us live up to them

3 / 12

@schmonz

#hackerkegeln

schmonz.com/talk
/2018-nuernberg

1. Introduction to Strangler (1/2)

"One of the natural wonders of [the Queensland coast] are the huge strangler vines. They seed in the upper branches of a fig tree and gradually work their way down the tree until they root in the soil. Over many years they grow into fantastic and beautiful shapes, meanwhile strangling and killing the tree that was their host."
--Martin Fowler

4 / 12