使用迭代和推入数组重构Ruby If/Else

Question

我正在尝试清理一个遍历推入数组的数据的方法。大概是这样的：

def sort_by_title(authors)
 general = []
 fiction = []
 factual = []
 food = []
 other = []

 authors.each do |a|
  if a.tag.include?('General')
   general << a
  elsif a.tag.include?('Historical')
    fiction << a if a.tag.include?('iction')
    factual <<a if a.tag.include?('actual')
  elseif a.tag.include?('Food')
    food << a
  else
    other << a
  end
 end
 (general + fiction + factual + food + other).flatten
end
end

鲁博科普正在用：Metrics/AbcSize and Metrix/Perceived Complexity攻击我。有没有更干净的方法可以这样做呢？

Answer 1

我会选择case

authors.each_with_object(Hash.new { |h, k| h[k] = [] }) do |a, hash|
  case a.tag
  when /General/ then h[:general] << a
  when /Historical.*iction/ then h[:fiction] << a
  when /Historical.*actual/ then h[:factual] << a
  when /Food/ then h[:food] << a
  else h[:other] << a
end.values.flatten

或者，使用Enumerable#sort_by使用更令人兴奋和语义正确的方法

authors.sort_by do |a|
  [
    10 if a.tag.include?('General'),
    if a.tag.include?('iction')
      8
    elsif if a.tag.include?('actual')
      6
    end if a.tag.include?('Historical'),
    4 if a.tag.include?('Food'),
    2
  ].compact.sum
end

Answer 2

您可以使用#group_by

def sort_by_title(authors)
  grouped = authors.group_by do |a| 
    if a.tag.include?('General')
      :general
    elsif a.tag.include?('Historical')
      :fiction if a.tag.include?('iction')
      :factual if a.tag.include?('actual')
    elsif a.tag.include?('Food')
      :food
    else
      :other
    end
  end
  grouped.values.flatten
end

编辑：

为了让它更清晰，你可以提取关于流派的方法：

class Author
  def genre
    if tag.include?('General')
      :general
    elsif tag.include?('Historical')
      :fiction if tag.include?('iction')
      :factual if tag.include?('actual')
    elsif tag.include?('Food')
      :food
    else
      :other
    end
  end
end

def sort_by_title(authors)
  authors.group_by(&:genre).values.flatten
end

Answer 3

您需要对它们进行分组还是排序？如果只是排序，是否可以使用带有查找字段的sort_by？

TAGS = {
  'General' => 1,
  'Fiction' => 2,
  'Factual' => 3,
  'Food' => 4,
  'Other' => 5
}

authors = [
  { name: 'Joe', tag: 'General' },
  { name: 'Sue', tag: 'Fiction' },
  { name: 'Sally', tag: 'Food' },
  { name: 'Oliver', tag: 'Factual' },
  { name: 'Bob', tag: 'Other' },
  { name: 'Billy', tag: 'General' }
]

sorted_authors =
  authors.sort_by do |author|
    TAGS[author[:tag]] # This would be author.tag in your example
  end

puts sorted_authors

收益率

{:name=>"Joe", :tag=>"General"}
{:name=>"Billy", :tag=>"General"}
{:name=>"Sue", :tag=>"Fiction"}
{:name=>"Oliver", :tag=>"Factual"}
{:name=>"Sally", :tag=>"Food"}
{:name=>"Bob", :tag=>"Other"}