Auto-generate op==?

J.E_Schotsman · February 13, 2016, 10:44am

I would like to see Swift auto-generate the == operator if a struct implements Equatable

I wrote up a proposal for this but I was told it needed more discussion before it could be reviewed.

jeschot/swift-evolution/blob/master/proposals/Swift proposal.txt

Feature name: provide default func ==(_:_:) for types declared Equatable

Proposal: SE-NNNN
Author: Jan E.Schotsman
Status: Awaiting review
Review manager: TBD

Introduction:

If all of a type's stored properties are Equatable it makes sense for Swift to provide a default equality implementation.

Motivation:

In a project where many large types are defined that need to be Equatable it gets cumbersome to write explicit equality functions for all types.
Swift-evolution thread: https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160125/007876.html

Proposed solution

If a type is declared Equatable, all its stored properties are Equatable and no func ==(_:_:) is defined by the developer the compiler will synthetisize a memberwise equality function.
(Recursiveness of this procedure is almost automatic)

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Obviously, it would only be able to do this if all the structs members implemented Equatable themselves.

Or provide a basis on which the developer can expand. See my proposal.

If Dave Sweeris is right and the proposal is currently difficult to implement then it'll have to wait...

Jan E.

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On Feb 12, 2016, at 11:21 PM, Daniel Tartaglia wrote: