swiftlint.yml

# swiftlint configuration
# https://github.com/realm/SwiftLint
#
# Install via Homebrew.
#
# Swiftlint is useful for catching some classes of error (e.g. non-weak delegate)
# However (IMO) the defaults include too many style rules, which need not be enforced for correctness.
# We disable some of the more egregious rules.
#
# See: https://github.com/realm/SwiftLint/blob/master/Rules.md

disabled_rules:
  # Force casting is perfectly acceptable when the type is known e.g. view.descendants { $0 is Foo } as! [Foo]
  # swiftlint already disables this warning in some cases (e.g. IBOutlet).
  - force_cast
  - todo
  # else, catch should be on the same line as the closing brace: sometimes this just doesn't read well.
  - statement_position
  - operator_whitespace
#  - closing_brace
  - closure_parameter_position
  # Just annoying - parameter names provide useful documentation
  - unused_closure_parameter
opt_in_rules:
  - array_init
  - closure_spacing
  - conditional_returns_on_newline
  - empty_count
  - fatal_error_message
  - first_where
  - force_unwrapping
  - implicit_return
  - multiline_arguments
  - multiline_parameters
  - overridden_super_call
  - override_in_extension
  - pattern_matching_keywords
  # e.g. super.loadView()
  - prohibited_super_call
  - redundant_nil_coalescing
  - trailing_closure
  - unneeded_parentheses_in_closure_argument
  # if 1 == foo { ...
  - yoda_condition
excluded:
  # Paths are relative to project dir.
  # Note: swiftlint support for globbing is unreliable (depends on working directory used when running swiftlint).
  # So we have to exclude Package.swift & .build explicitly using full (relative) paths.
  - Carthage
  - SyncthingBarTests
  - .build
  - Package.swift

# rule customisation
line_length:
  180
function_body_length:
  warning: 50
identifier_name:
  # Permit identifiers such as 'id'
  min_length: 2
  # excluded works (for some reason "allowed_symbols" does not)
  excluded: [x, y, i]
implicit_return:
  included:
    - closure
    - getter
file_length:
  ignore_comment_only_lines: true
custom_rules:
  # More permissive version of operator_usage_whitespace which allows literal fractions e.g. 1/6
  custom_operator_usage_whitespace:
    message: "Operators should be surrounded by a 1 space when they are being used."
    severity: warning
    # Notes:
    # We only need worry about the case when there are no spaces on *both* sides of the operator (e.g. 1*2)
    # Othewise the Swift compiler will flag invalid unary operator usage.
    #
    # Rules:
    # 1. a*b, but not "(*" which is used for @available(*,
    # 2. a[+-]b, but not 1e-9 or 1e+9 or &+ etc (overflow operators).
    # 3. Division of a non-digit e.g. foo/2
    # 4. Division by a non-digit e.g. 2/foo
    # Note that in 3 & 4 we can't use word match (\w) because it includes integers.
    # 5. Multiple spaces before operator.
    # 6. Multiple spaces after operator.
    regex: "(\\S(?<!\\()\\*)|(\\S(?<!\\de|&)[\\+\\-])|([a-zA-Z\\)\\.]\\d*/\\S)|(\\S\\/[a-zA-Z\\(])|(\\S {2,}[+\\-\\*\\/&\\|])|([+\\-\\*\\/&\\|] {2,})"
    match_kinds:
      - identifier
      - number
  prefer_property_to_getter:
    message: "Prefer computed properties to get functions."
    severity: warning
    regex: "(func get\\w+\\(\\s*\\)(?!\\s*throws))"
  prefer_property_to_setter:
    message: "Prefer computed properties to set functions."
    severity: warning
    regex: "(?<!@IBAction )(func set\\w+\\(\\s*_\\s+[\\s\\w]+:[\\s\\w\\!]+\\)(?!\\s*throws))"