delay's Introduction

Deprecated

This project is deprecated, and will not be updated in future. Memo is a complete replacement for its functionality, and is better-tested, -documented, and -spoken.

Delay

This is a Swift microframework which implements a lazily-evaluated memoizing wrapper type.

It’s a bit like a promise.

Why not just use a closure?

Closures do not automatically memoize; Delay will evaluate zero or one times, whereas closures will evaluate every time they are called.
Closures are currently subject to non-fixed multi-payload enum layout errors; since Delay is a class, it does not cause these problems for enum layout.

Use

func expensiveComputation() -> Int
let delayedResult = delay(expensiveComputation())
let actualResult = delay.force() // explicitly force it
let otherActualResult: Int = delay // use the implicit __conversion

See Delay.swift for more details.

Integration

Add this repo as a submodule in e.g. External/Delay:

 git submodule add https://github.com/robrix/Delay.git External/Delay

Drag Delay.xcodeproj into your .xcworkspace/.xcodeproj.
Add Delay.framework to your target’s Link Binary With Libraries build phase.
You may also want to add a Copy Files phase which copies Delay.framework (and any other framework dependencies you need) into your bundle’s Frameworks directory. If your target is a framework, you may instead want the client app to include Delay.framework.

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