swiftlang/swift

[SR-3550] Compound name syntax for functions with no params

Open

#46,138 opened on Jan 5, 2017

View on GitHub
 (11 comments) (0 reactions) (0 assignees)Swift (69,989 stars) (10,719 forks)batch import
compilerdeclaration namesgood first issueswift evolution proposal needed

Description
Previous ID SR-3550
Radar None
Original Reporter @jtbandes
Type Improvement
Votes 0
Component/s Compiler
Labels Improvement, StarterProposal
Assignee None
Priority Medium

md5: 9e54c0bcc3910a9a4c3dc549a118933b

relates to:

  • SR-1408 NSArray indexesOfObjectsPassingTest cannot be called in Swift 3

Issue Description:

The "compound name" of a function can be used to resolve ambiguities with argument labels, e.g. foo(x:) or foo(_:). However, there's no such shortcut to specify an overload that has no arguments. A workaround is to use its type with as:

import Foundation
class C: NSObject {
    func foo() {}
    func foo(x: Int) {}
}

#selector(C.foo)  // error: ambiguous use of 'foo'
#selector(C.foo(x:))  // resolve ambiguity with compound name
#selector(C.foo as (C) -> () -> ())  // resolve ambiguity by specifying type

But it'd be nice to have some way of doing this without specifying the type. Perhaps foo(_) (for symmetry with foo(_:))?

Contributor guide

Tech stack
swift
Domain
developer experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Swiftcompiler internalsselector resolution
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Review the issue description and comments for any additional context, particularly the relationship with SR 1408. Examine the Swift compiler source code for compound name resolution, likely in the lib/Sema or lib/Parse directory. Understand how compound names like `foo(x:)` are resolved and propose an extension to handle zero argument cases, possibly using `foo( )` syntax. Seek feedback from maintainers on the proposed syntax and implementation approach.