What is Singleton?
A type that allows only one shared instance in the app. Useful for coordinators, sometimes overused for global state.
3 callers · 1 shared instance
Singleton guarantees…
Write it in your own words in the app.
In real work
Singleton: Analytics.shared logs from anywhere, but we inject a mock in tests.
In the illustration
Three arms reach in from three stations and each comes back touching the same tethered tag #1; a lever that would build a second one stays locked.
The app has four singleton types in your coding agent. Keep the one for the audio session, turn the other three into injected dependencies, and explain why each one did not need to be global.
Try it now
The fastest way to learn a word is to use it. Open this line in the agent you already work in and watch what it does. Change the tool to the one you use.
Go further
01Practice
Make it stick
One term a day, a short quiz, and sentence practice that checks your own words.
02Verify
Prove you know it
Pass the quiz and keep it in a Skills Wallet you can share with anyone who needs proof.
03Career
Find the work that uses it
See which roles lean on this vocabulary, and what they pay in year one.
More in Foundations
All terms →
Learn the next term tomorrow.
Google gives a definition. Prompthaus pairs each term with how it shows up in standups, PRs, prompts, and design reviews. Then it quizzes you until the word sticks. One term a day on iPhone.
