Prefer Key Path

Use a key path argument instead of a closure with property access

• Identifier: prefer_key_path
• Enabled by default: No
• Supports autocorrection: Yes
• Kind: idiomatic
• Analyzer rule: No
• Minimum Swift compiler version: 5.2.0
• Default configuration:

  Key	Value
  severity	warning
  restrict_to_standard_functions	true

Non Triggering Examples

f {}

f { $0 }

f { $0.a }

let f = { $0.a }(b)

//
// restrict_to_standard_functions: false
//

f {}

//
// restrict_to_standard_functions: false
//

f() { g() }

//
// restrict_to_standard_functions: false
//

f { a.b.c }

//
// restrict_to_standard_functions: false
//

f { a, b in a.b }

//
// restrict_to_standard_functions: false
//

f { (a, b) in a.b }

//
// restrict_to_standard_functions: false
//

f { $0.a } g: { $0.b }

//
// restrict_to_standard_functions: false
//

[1, 2, 3].reduce(1) { $0 + $1 }

f.map(1) { $0.a }

f.filter({ $0.a }, x)

#Predicate { $0.a }

let transform: (Int) -> Int = nil ?? { $0.a }

Triggering Examples

f.map ↓{ $0.a }

f.filter ↓{ $0.a }

f.first ↓{ $0.a }

f.contains ↓{ $0.a }

f.contains(where: ↓{ $0.a })

//
// restrict_to_standard_functions: false
//

f(↓{ $0.a })

//
// restrict_to_standard_functions: false
//

f(a: ↓{ $0.b })

//
// restrict_to_standard_functions: false
//

f(a: ↓{ a in a.b }, x)

f.map ↓{ a in a.b.c }

f.allSatisfy ↓{ (a: A) in a.b }

f.first ↓{ (a b: A) in b.c }

f.contains ↓{ $0.0.a }

f.compactMap ↓{ $0.a.b.c.d }

f.flatMap ↓{ $0.a.b }

//
// restrict_to_standard_functions: false
//

let f: (Int) -> Int = ↓{ $0.bigEndian }

transform = ↓{ $0.a }