azure-pipelines-yaml/[DEV]-Programming-advice-and-tips-&-tricks.md

This page is a collection of FYI- and TIL-items that spotlights particular useful utilities or programming patterns that aren't obvious or little known. Take them as an offering and not as some must-do.

Disposable utils

• The Disposable base class makes it easy for subclasses to _register values that should be disposed of when the instance is disposed of.
• DisposableStore safely manages a collection of disposable values. It is preferred over IDisposable[].
• DisposableMap manages a map where the values are disposables. It helps you avoid some tricky lifecycle bugs vs implementing a Map<K, IDisposable> yourself.
• MutableDisposable safely manages a disposable value that can change over this. This prevents bugs where you forget to dispose of the old value when overwriting it with a new value.

Data structures

• native Map and Set are sorted by insertion order 💡 this is a little-know but can come handy
• ResourceMap and ResourceSet which are normal maps/sets but keyed by URI
• LRUCache is a map with recency and trimming abilities
• TernarySearchTree is map-like with the ability to lookup sub and super-strings (useful for path containment)
• SkipList is a map which is sorted based on a custom comparator function
• LinkedList like arrays but with faster removal/insertion

String/array utils

The modules src/vs/base/common/arrays.ts and src/vs/base/common/strings.ts have many very useful utilities when dealing with arrays or strings.

Iterables

The src/vs/base/common/iterator.ts modules contains utilities for working with iterables. Iterables can be a better alternative than arrays because they enforce readonly-ness by design and hence saving Array.slice-calls

Lazy, Async, Idle

We have utils to delay certain operations or values

• Lazy<T> a lazy value is computed only when accessed for the first time
• IdleValue<T> is similar to Lazy but uses browser idle times to eagerly compute its value. Implements the "idle until urgent" pattern, see: https://philipwalton.com/articles/idle-until-urgent/
• runWhenIdle is our wrapper around browsers window.requestIdleCallback-function
• scheduleAtNextAnimationFrame and runAtThisOrScheduleAtNextAnimationFrame allows to join this or the next browser animation frame