The Magic Function principle

"Hey how does the foobulizer work again?"

Ugh not this again. You've been answering this same damn question for months. How are they still not getting it?? 🙄

It's simple!

You take the gnasher, connect it to the third function call from the left on a full moon, or the fourth one from top, if it's Sunday, then you plug into the fantalizer, add 3 lines of code using the in-house configuration language built from JSON, stand on your right leg, hold the left nostril, and voila: the foobulizer.

I mean seriously, are they all stupid?

Write the docs

Your team is smart.

When you get (or ask) the same question over and over, that's a symptom. The problem is the codebase. Or the architecture. Or the data model. Or the docs.

Your team can't help itself. They need you.

Fantastic job security aaaaand that's why senior engineers get nothing done. There's no time. 💩

When you answer the same question 3 times, write it down. Share the link.

When they ask again, edit and share the link.

Your doc won't always answer all the nuance of a question but it helps. Gets you on common ground, makes the chat more productive.

And the more you write, the less you have to keep in your head. Mine has the memory of a goldfish 😇

The Magic Function

You know what's even better than up-to-date docs? Not needing docs.

Imagine if instead of a complex 6 step process you could start the foobulizer with startFoobulizer().

We used to have this problem at work. We still do but not with that part 😛

The Magic Function saved my butt

Verifying insurance was my first introduction to "Holy shit health tech is something else".

The process goes like this: Get your info, maybe use what exists, talk to an API, see if it's valid, check a sea of inscrutable codes, decide if your insurance supports this appointment at this time (yes it changes), and a bunch other details.

You don't want to deal with this as a user.

Heck, I didn't wanna deal with it as a programmer! Confusing, terrible, makes-no-sense.

We had an Insurance module, but it was hard to hold. You had to call the right functions in the right sequence at the right time.

Get it wrong and the company doesn't get paid.

I got it wrong. Five times 😅

Edge case after edge case, bug after bug, meeting after meeting. 3 of us working on this stupid thing.

We had docs, we had code, yet we couldn't make it work.

Until one day the dude who grokked the business logic said "Screw this, this is bullshit."

He built a new function: Insurance.verify(user, appointment).

And oh my god it was beautiful. Cut through all the crap. You call this method, give it a user and an appointment, and it does it all for you. Standing on the right leg holding its left nostril and all! 😍

Nobody has asked an insurance question since.

Why The Magic Function works

The Magic Function is a high level method that does the thing the whole thing and nothing but the thing.

Forget reading and understanding docs. Forget writing and updating docs. Just make it work.

You do the work so your team doesn't have to. Like Penn & Teller say:

Sometimes magic is just someone spending more time on something than anyone else might reasonably expect. ~ Teller of Penn&Teller fame

You write The Magic Function when you see that code always goes together. You always make this DB update after that API call. You always call these 3 functions together. You always ...

The Magic Function frees your team from that complexity. Instead of worrying about the details, they focus on their problem. 🧙

Best part: they'll find your function on their own. No questions, no confusion.

Engineers always find a way. Help them find the way.

Ye olde unix philosophy??

The opposite of The Magic Function is the unix philosophy – lots of small composable utilities.

Make each program do one thing well. To do a new job, build afresh rather than complicate old programs by adding new "features". Expect the output of every program to become the input to another, as yet unknown, program

How you read this depends on your idea of "one thing".

Is one thing to verify insurance, or to call an API for 1 out of 50 different ways it needs to be called depending on circumstance? 🤔

It's fractal. Single responsibility all the way down. A magic function calls other magic functions.

You wouldn't wanna think about optimizing DOM updates to draw a button, just like your HTML rendering shouldn't think about where the HTML is from.

Write functions, mostly magic. Think fractals.

✌️

Cheers,
~Swizec

PS: how to start a 1928 Ford is a 20min video. These days you press a button and go. When's the last time you read the instruction manual for a car?