Shorthand Argument

Shorthand arguments like $0, $1, etc. in closures can be confusing. Avoid using them too far away from the beginning of the closure. Optionally, while usage of a single shorthand argument is okay, more than one or complex ones with field accesses might increase the risk of obfuscation.

• Identifier: shorthand_argument
• Enabled by default: No
• Supports autocorrection: No
• Kind: style
• Analyzer rule: No
• Minimum Swift compiler version: 5.0.0
• Default configuration:

  Key	Value
  severity	warning
  allow_until_line_after_opening_brace	4
  always_disallow_more_than_one	false
  always_disallow_member_access	false

Non Triggering Examples

f { $0 }

f {
    $0
  + $1
  + $2
}

f { $0.a + $0.b }

//
// allow_until_line_after_opening_brace: 1
//

f {
    $0
  +  g { $0 }

Triggering Examples

f {
    $0
  + $1
  + $2

  + ↓$0
}

//
// allow_until_line_after_opening_brace: 5
//

f {
    $0
  + $1
  + $2
  +  5
  + $0
  + ↓$1
}

//
// always_disallow_more_than_one: true
//

f { ↓$0 + ↓$1 }

//
// allow_until_line_after_opening_brace: 3
// always_disallow_member_access: true
//

f {
    ↓$0.a
  + ↓$0.b
  + $1
  + ↓$2.c
}