jspahrsummers / enemy-of-the-state

My talk explaining what state is and why it's so harmful

Enemy of the State

Presented at CocoaConf Mini Austin in April 2014, CocoaConf Las Vegas in September 2014, and the Functional Swift Conference (video) in December 2014.

[This presentation](Enemy of the State.md) is designed for Deckset theme “Next”.

Thanks to @lukehefson for designing the original slides!

References

Here are some links to material referenced in the talk:

• Simple Made Easy by Rich Hickey
• Out of the Tar Pit by Moseley and Marks
• Mutability, aliasing, and the caches you didn’t know you had by Andy Matuschak
• Boundaries by Gary Bernhardt
• “Advanced iOS Application Architecture and Patterns” from WWDC 2014 by Andy Matuschak and Colin Barrett
• ReactiveCocoa
• Haskell's official website, or my preferred tutorial, Real World Haskell
• Elm

enemy-of-the-state's Issues

Link to or save fonts in repository

Need more content

What I have planned right now will probably max out at 30 slides, which won't fill enough time. If anyone has ideas for other territory to cover, please let me know.

Open source this repository?

No matter what, I'm going to post the slides from the talk on Speaker Deck.

However, I don't know whether to leave this repository private or make it public. Would the artifacts of this repository (the issues, pull requests, and history) be interesting to the public?

Styling

Need it sooo bad.

Feedback from CocoaConf Mini Austin 2014

I'm giving this talk again soon, so I'm going to do my best to address some of the speaker feedback I received from the last time.

Here it is, aggregated. It's kinda contradictory in places, but I think the overall gist is pretty clear: add more concrete examples, and figure out what to do with the RAC slides that got kinda shoehorned in.

What did you like best about this session?

• The brief explanations of ReactiveCocoa and MVVM
• The arguments were articulated and presented well, with good explanations
• It was a good summary of the issues with state, and a great introduction to reducing it for less error-prone programs
• It presented new and different ideas that aren't talked about much
• The explanation about the exponential complexity of state
• The length and value of Q&A afterward
• The design of the slide deck (h/t @lukehefson)
• There was a good flow
• The copious references to additional references
• The distinction drawn between simple and easy

What were the problems with this session?

• Wanted more explanation about ReactiveCocoa, how it works, and how it helps
• Came across as an ad for ReactiveCocoa
• Needed more concrete, real world, code-focused examples of the problems and solutions
• A full demo app would've been helpful
• The talk should've been longer
• There was too much to cover in 30–40 minutes
• More questions were raised than answered
• The arguments against singletons weren't convincing enough for Gang of Four advocates, especially without examples
• It's hard knowing how to apply the points
• It was too pedantic
• There wasn't a focused, succinct takeaway
• Needed more explanation of why this is such a problem in app development (especially cache invalidation)

Alternate name?

I prefer "Enemy of State" over "Enemy of the State".

The subtle play on words appeals to my sense of humour. So it could just be me 🚎

Novel example of global state

Not sure if this dovetails nicely into your presentation, but I just ran into a project's build system with an amusing expression of the global state problem:

• The build system installs its products in a global location on the file system.
• The build system has access to the globally installed products during the build.
• The build system grew dependencies on products globally installed by previous iterations of the build system.
• All of the developers have been regularly building and installing, thus updating their global state, so nobody noticed.
• A cyclic dependency now exists, and the project can no longer be built from a clean checkout without access to the previously built+installed global state.
• A new developer comes along ...

This is not unlike the webs of inter/cyclic-dependence in code that emerge entirely by accident due to the existence of largely unbounded global state interdependence.

Immutability

const plays a key role in using immutability in C / C++.
Not so much in Obj-C I guess...
Do you want to discuss it in the section on immutability? Just a suggestion.