Class: RuboCop::Cop::Layout::EmptyLineBeforeGuardClause

Inherits:
Base
  • Object
show all
Defined in:
lib/rubocop/cop/layout/empty_line_before_guard_clause.rb

Overview

Requires a blank line before a guard clause that follows ordinary code. A guard clause breaks the flow, so it has to be findable at a glance rather than read for — the same reason a multi-line statement is set off from its neighbours.

Consecutive guard clauses are one block and stay glued together: the run is what the reader scans, and blank lines inside it would break the shape instead of revealing it. Only the first clause of a run needs the blank line above, and a guard that opens a body needs none because the def or do already delimits it.

What counts as a guard clause is guard_clause? from rubocop-ast, which covers return, break, next, raise and fail.

The blank line after the run is the stock Layout/EmptyLineAfterGuardClause, which this cop mirrors rather than replaces — enable both to get a run that is set off on both sides.

Detection-only (no autocorrect), matching the sibling Layout/MultilineStatementSpacing: where a comment sits above the clause the blank line belongs above the comment, and that placement needs validation against the real repos before it is applied for anyone.

Examples:

# bad
def foo
  bar
  return if baz?

  qux
end

# good
def foo
  bar

  return if baz?

  qux
end

# good — a run of guard clauses stays together
def foo
  return if baz?
  return if qux?

  bar
end

# good — nothing above it to separate from
def foo
  return if baz?

  bar
end

Constant Summary collapse

MSG = 
'Add a blank line before the guard clause.'

Instance Method Summary collapse

Instance Method Details

#on_begin(node) ⇒ Object 



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# File 'lib/rubocop/cop/layout/empty_line_before_guard_clause.rb', line 67

def on_begin(node)
  node.children.each_cons(2) do |previous, current|
    next unless guard_clause?(current)
    next if guard_clause?(previous)
    next if blank_line_between?(previous, current)

    add_offense(current)
  end
end