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SDGCaching

⚠ This project is obsolete. It has been superseded by SDGCornerstone. ⚠

SDGCaching automates caching for results of complex or time‐consuming functions.

רַק הִשָּׁמֶר לְךָ וּשְׁמֹר נַפְשְׁךָ מְאֹד פֶּן־תִּשְׁכַּח אֶת־הַדְּבָרִים אֲשֶׁר־רָאוּ עֵינֶיךָ וּפֶן־יָסוּרוּ מִלְּבָבְךָ כֹּל יְמֵי חַיֶּיךָ וְהוֹדַעְתָּם לְבָנֶיךָ וְלִבְנֵי בָנֶיךָ׃
Only watch yourself, and guard your soul carefully lest you forget the things your eyes have seen and let them fade from your heart all the days of your life. Make them known to your sons and to your sons’ sons.
―‎משה/Moshe

Features

Automated caching for results of complex or time‐consuming functions via cached(in::).

(For a list of related projecs, see here.)

Importing

SDGCaching is intended for use with the Swift Package Manager.

Simply add SDGCaching as a dependency in Package.swift:

let package = Package(
    ...
    dependencies: [
        ...
        .Package(url: "https://github.com/SDGGiesbrecht/SDGCaching", versions: "2.1.0" ..< "3.0.0"),
        ...
    ]
)

SDGCaching can then be imported in source files:

import SDGCaching

Example Usage

import SDGCaching

// This example uses SDGCaching to cache the computed properties of a structure.

private struct Number {

    // MARK: - Initialization

    init(value: Int) {
        self.value = value
    }

    // MARK: - Stored Property

    var value: Int {
        willSet {
            // Empty the cache whenever the value property changes.
            cache = Cache()
        }
    }

    // MARK: - Cache

    private class Cache {
        var square: Int?
        var powers: [Int: Int] = [:]
    }
    private var cache = Cache()

    // MARK: - Computed Properties

    // These will only be executed once as long as the value property stays the same.
    // When the value property changes, they will be re‐executed the next time they are needed.

    var square: Int {
        return cached(in: &cache.square) {

            var result = 0
            for _ in 1 ... value {
                result += value
            }
            return result
        }
    }

    func toPower(of exponent: Int) -> Int {

        // This makes use of a dictionary to separate the cache for each exponent.
        return cached(in: &cache.powers[exponent]) {

            var result = 0
            for _ in 1 ... exponent {
                for _ in 1 ... value {
                    result += value
                }
            }
            return result
        }
    }
}

About

The SDGCaching project is maintained by Jeremy David Giesbrecht.

If SDGCaching saves you money, consider giving some of it as a donation.

If SDGCaching saves you time, consider devoting some of it to contributing back to the project.

Ἄξιος γὰρ ὁ ἐργάτης τοῦ μισθοῦ αὐτοῦ ἐστι.
For the worker is worthy of his wages.
―‎ישוע/Yeshuʼa