Discouraged Default Parameter

Default parameter values should not be used in functions with certain access levels.

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

  Key	Value
  severity	warning
  disallowed_access_levels	[internal, package]

Rationale

By discouraging default parameter values in functions, that are exposed to other source files in the module or package and their consumers, we can promote call sites and reduce the likelihood of bugs caused by unexpected (or changed) default values being used.

Non Triggering Examples

public func foo(bar: Int = 0) {}

open func foo(bar: Int = 0) {}

func foo(bar: Int) {}

private func foo(bar: Int = 0) {}

fileprivate func foo(bar: Int = 0) {}

public init(value: Int = 42) {}

//
// disallowed_access_levels: [private]
//

func foo(bar: Int = 0) {}

Triggering Examples

func foo(bar: Int ↓= 0) {}

internal func foo(bar: Int ↓= 0) {}

package func foo(bar: Int ↓= 0) {}

func foo(bar: Int ↓= 0, baz: String ↓= "") {}

init(value: Int ↓= 42) {}

//
// disallowed_access_levels: [private]
//

private func foo(bar: Int ↓= 0) {}

//
// disallowed_access_levels: [fileprivate]
//

fileprivate func foo(bar: Int ↓= 0) {}