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[SR-238] Support throwing subscripts #42860

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swift-ci opened this issue Dec 15, 2015 · 3 comments
Closed

[SR-238] Support throwing subscripts #42860

swift-ci opened this issue Dec 15, 2015 · 3 comments
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@theblixguy
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compiler The Swift compiler in itself declarations Feature: declarations error handling feature A feature request or implementation improvement subscript Feature: Subscript declarations swift evolution implemented Flag → feature: A feature that was approved through the Swift evolution process and implemented throws & rethrows Feature → error handling: throws & rethrows

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@swift-ci
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Previous ID SR-238
Radar None
Original Reporter anviking (JIRA User)
Type Improvement
Additional Detail from JIRA
Votes 24
Component/s
Labels Improvement, LanguageFeatureRequest
Assignee @theblixguy
Priority Medium

md5: d1f830bfd05395ee30fb2819cb12b391

relates to:

  • SR-115 Support generic constraints in subscripts

Issue Description:

Support for throwing subscripts would together with generic ones be really nice for JSON mapping/deserializing libraries like mine https://github.com/Anviking/Decodable. It would make subscripts an alternative to custom operators.

For example:
subscript<T: SomeProtocol>(key: String) throws -> T

Would most likely be useful on its own for a lot of other things as well.
@theblixguy
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There is now a WIP implementation that supports throwable getters and setters which can be used inside both computed properties and subscripts. There's still a bit of work left, but hopefully it should be finished soon: #22749

@xAlien95
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xAlien95 commented Jul 7, 2021

Throwing subscripts are available in Swift 5.5 due to SE-0310 Effectful Read-only Properties. Should this issue be marked as resolved?

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
@endeavour42
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endeavour42 commented Apr 10, 2024 •
edited

SE-0310 only allows throwing getter-only subscripts, setters are prohibited when getter is marked as throwing. I believe having a throwing subscript with both getter and setter would be handy:

let element = try array[at: index]
try array[at: index] = value

@AnthonyLatsis AnthonyLatsis added compiler The Swift compiler in itself error handling subscript Feature: Subscript declarations declarations Feature: declarations throws & rethrows Feature → error handling: throws & rethrows swift evolution implemented Flag → feature: A feature that was approved through the Swift evolution process and implemented labels Apr 10, 2024
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@theblixguy theblixguy

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compiler The Swift compiler in itself declarations Feature: declarations error handling feature A feature request or implementation improvement subscript Feature: Subscript declarations swift evolution implemented Flag → feature: A feature that was approved through the Swift evolution process and implemented throws & rethrows Feature → error handling: throws & rethrows
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@endeavour42 @theblixguy @xAlien95 @swift-ci @AnthonyLatsis