brew "swiftlint"

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Helps you transition from mutable string literals to frozen string literals. It will add the # frozen_string_literal: true magic comment to the top of files to enable frozen string literals. Frozen string literals may be default in future Ruby. The comment will be added below a shebang and encoding comment. The frozen string literal comment is only valid in Ruby 2.3+.

Note that the cop will accept files where the comment exists but is set to false instead of true.

To require a blank line after this comment, please see Layout/EmptyLineAfterMagicComment cop.

Safety:

This cop's autocorrection is unsafe since any strings mutations will change from being accepted to raising FrozenError, as all strings will become frozen by default, and will need to be manually refactored.

Example: EnforcedStyle: always (default)

# The `always` style will always add the frozen string literal comment
# to a file, regardless of the Ruby version or if `freeze` or `<<` are
# called on a string literal.
# bad
module Bar
  # ...
end

# good
# frozen_string_literal: true

module Bar
  # ...
end

# good
# frozen_string_literal: false

module Bar
  # ...
end

Example: EnforcedStyle: never

# The `never` will enforce that the frozen string literal comment does
# not exist in a file.
# bad
# frozen_string_literal: true

module Baz
  # ...
end

# good
module Baz
  # ...
end

Example: EnforcedStyle: always_true

# The `always_true` style enforces that the frozen string literal
# comment is set to `true`. This is a stricter option than `always`
# and forces projects to use frozen string literals.
# bad
# frozen_string_literal: false

module Baz
  # ...
end

# bad
module Baz
  # ...
end

# good
# frozen_string_literal: true

module Bar
  # ...
end

brew "swiftlint"

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Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

brew "blender/homebrew-tap/rome"

Close

Checks if uses of quotes match the configured preference.

Example: EnforcedStyle: single_quotes (default)

# bad
"No special symbols"
"No string interpolation"
"Just text"

# good
'No special symbols'
'No string interpolation'
'Just text'
"Wait! What's #{this}!"

Example: EnforcedStyle: double_quotes

# bad
'Just some text'
'No special chars or interpolation'

# good
"Just some text"
"No special chars or interpolation"
"Every string in #{project} uses double_quotes"

open *.xcodeproject

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Use ./*glob* or -- *glob* so names with dashes won't become options.

Problematic code:

rm *

Correct code:

rm ./*

or

rm -- *

Rationale

Since files and arguments are strings passed the same way, programs can't properly determine which is which, and rely on dashes to determine what's what.

A file named -f (touch -- -f) will not be deleted by the problematic code. It will instead be interpreted as a command line option, and rm will even report success.

Using ./* will instead cause the glob to be expanded into ./-f, which no program will treat as an option.

Similarly, -- by convention indicates the end of options, and nothing after it will be treated like flags (except for some programs possibly still special casing - as e.g. stdin).

Note that changing * to ./* in GNU Tar parameters will add ./ prefix to path names in the created archive. This may cause subtle problems (eg. to search for a specific file in archive, the ./ prefix must be specified as well). So using -- * is a safer fix for GNU Tar commands.

For more information, see "Filenames and Pathnames in Shell: How to do it Correctly".

Notice

Original content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.

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Looks for trailing blank lines and a final newline in the source code.

Example: EnforcedStyle: final_newline (default)

# `final_newline` looks for one newline at the end of files.

# bad
class Foo; end

# EOF

# bad
class Foo; end # EOF

# good
class Foo; end
# EOF

Example: EnforcedStyle: finalblankline

# `final_blank_line` looks for one blank line followed by a new line
# at the end of files.

# bad
class Foo; end
# EOF

# bad
class Foo; end # EOF

# good
class Foo; end

# EOF

Close

Looks for trailing whitespace in the source code.

Example:

# The line in this example contains spaces after the 0.
# bad
x = 0

# The line in this example ends directly after the 0.
# good
x = 0

Example: AllowInHeredoc: false (default)

# The line in this example contains spaces after the 0.
# bad
code = <<~RUBY
  x = 0
RUBY

# ok
code = <<~RUBY
  x = 0 #{}
RUBY

# good
trailing_whitespace = ' '
code = <<~RUBY
  x = 0#{trailing_whitespace}
RUBY

Example: AllowInHeredoc: true

# The line in this example contains spaces after the 0.
# good
code = <<~RUBY
  x = 0
RUBY

export SRCROOT=`pwd`

Close

Declare and assign separately to avoid masking return values.

Problematic code:

export foo="$(mycmd)"

Correct code:

foo=$(mycmd)
export foo

Rationale:

In the original code, the return value of mycmd is ignored, and export will instead always return true. This may prevent conditionals, set -e and traps from working correctly.

When first marked for export and assigned separately, the return value of the assignment will be that of mycmd. This avoids the problem.

Exceptions:

If you intend to ignore the return value of an assignment, you can either ignore this warning or use

foo=$(mycmd) || true
export foo

Shellcheck does not warn about export foo=bar because bar is a literal and not a command substitution with an independent return value. It also does not warn about local -r foo=$(cmd), where declaration and assignment must be in the same command.

Notice

Original content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.

Close

Looks for trailing whitespace in the source code.

Example:

# The line in this example contains spaces after the 0.
# bad
x = 0

# The line in this example ends directly after the 0.
# good
x = 0

Example: AllowInHeredoc: false (default)

# The line in this example contains spaces after the 0.
# bad
code = <<~RUBY
  x = 0
RUBY

# ok
code = <<~RUBY
  x = 0 #{}
RUBY

# good
trailing_whitespace = ' '
code = <<~RUBY
  x = 0#{trailing_whitespace}
RUBY

Example: AllowInHeredoc: true

# The line in this example contains spaces after the 0.
# good
code = <<~RUBY
  x = 0
RUBY

export SRCROOT=`pwd`

Close

Use $(STATEMENT) instead of legacy `STATEMENT`

Problematic code

echo "Current time: `date`"

Correct code

echo "Current time: $(date)"

Rationale

Backtick command substitution `STATEMENT` is legacy syntax with several issues.

1. It has a series of undefined behaviors related to quoting in POSIX.
2. It imposes a custom escaping mode with surprising results.
3. It's exceptionally hard to nest.

$(STATEMENT) command substitution has none of these problems, and is therefore strongly encouraged.

Exceptions

None.

See also

• http://mywiki.wooledge.org/BashFAQ/082

Notice

Original content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.

  warn('Library files were updated without test coverage.  

Close

Looks for trailing whitespace in the source code.

Example:

# The line in this example contains spaces after the 0.
# bad
x = 0

# The line in this example ends directly after the 0.
# good
x = 0

Example: AllowInHeredoc: false (default)

# The line in this example contains spaces after the 0.
# bad
code = <<~RUBY
  x = 0
RUBY

# ok
code = <<~RUBY
  x = 0 #{}
RUBY

# good
trailing_whitespace = ' '
code = <<~RUBY
  x = 0#{trailing_whitespace}
RUBY

Example: AllowInHeredoc: true

# The line in this example contains spaces after the 0.
# good
code = <<~RUBY
  x = 0
RUBY