Archival & Serialization: What's meant by contrasting type un/safety of existing JSON serializers?

jeremyw.sherman · 2017-06-05T15:22:02.000Z

What does the Archival & Serialization SE-0166 mean by:

Some libraries, like SwiftyJSON, do this [interface between JSON and

Swift] at the cost of type safety; others, like ObjectMapper and Argo
below, maintain type safety by offering archival functionality for JSON
types (

github.com

apple/swift-evolution/blob/main/proposals/0166-swift-archival-serialization.md#jsonserialization-friction-and-third-party-solutions-motivation

# Swift Archival & Serialization

* Proposal: [SE-0166](0166-swift-archival-serialization.md)
* Authors: [Itai Ferber](https://github.com/itaiferber), [Michael LeHew](https://github.com/mlehew), [Tony Parker](https://github.com/parkera)
* Review Manager: [Doug Gregor](https://github.com/DougGregor)
* Status: **Implemented (Swift 4)**
* Decision Notes: [Rationale](https://forums.swift.org/t/accepted-se-0166-swift-archival-serialization/5780)
* Implementation: [apple/swift#9004](https://github.com/apple/swift/pull/9004)

## Introduction

Foundation's current archival and serialization APIs (`NSCoding`, `NSJSONSerialization`, `NSPropertyListSerialization`, etc.), while fitting for the dynamism of Objective-C, do not always map optimally into Swift. This document lays out the design of an updated API that improves the developer experience of performing archival and serialization in Swift.

Specifically:

* It aims to provide a solution for the archival of Swift `struct` and `enum` types
* It aims to provide a more type-safe solution for serializing to external formats, such as JSON and plist

## Motivation

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)

I missed the review period (mea culpa), but I'd like to understand where
the authors are coming from here.

My first questions were:

- How is SwiftyJSON type-unsafe?
- How does "offering archival functionality for JSON types" as in Argo or
ObjectMapper recover type-safety?

On further thought, I don't think type-un/safety is what's at play here,
but I'm having trouble working out what was meant by that so I can rephrase
in my own terms. Perhaps one of the authors can elaborate?

Thanks!

···

--
Jeremy W. Sherman
https://jeremywsherman.com/