迴避使用if語句：縮短代碼

Question

我觀看了https://gorails.com/blog/refactoring-if-statements的視頻，但正在尋找一種更簡潔的方式來避免使用多個if或case語句。 以下工作

  def process(input) 
       commands = { 
        :q => Proc.new { puts "Goodbye" }, 
        :tweet => Proc.new { puts "tweeting" }, 
        :dm => Proc.new { puts "direct messaging"}, 
        :help => Proc.new { puts "helping"} 
       } 
       commands[input.to_sym].call 
      end 

      process "tweet" 

但我怎麼能進一步縮短呢？我嘗試以下

  def process(input) 
       commands = { 
        :q => { puts "Goodbye" }, 
        :tweet => { puts "tweeting" }, 
        :dm => { puts "direct messaging"}, 
        :help => { puts "helping"} 
       } 
       commands[input.to_sym].to_proc.call 
      end 

      process "tweet" 

但後來我得到的錯誤

  # syntax error, unexpected tSTRING_BEG, expecting keyword_do or '{' or '(' 
      #  :q => { puts "Goodbye" }, 
      #     ^

任何建議嗎？

Answer 1

使用lambda語法

def process(input) 
    commands = { 
    :q => ->{ puts "Goodbye" }, 
    :tweet => ->{ puts "tweeting" }, 
    :dm => ->{ puts "direct messaging"}, 
    :help => ->{ puts "helping"} 
    } 
    commands[input.to_sym].to_proc.call 
end 

process "tweet" 

使用新的Hash語法可以進一步縮短這個：

def process(input) 
    { 
    q: ->{ puts "Goodbye" }, 
    tweet: ->{ puts "tweeting" }, 
    dm: ->{ puts "direct messaging"}, 
    help: ->{ puts "helping"} 
    }[input.to_sym].call 
end 

process "tweet" 

Answer 2

我不知道是否你建議或者我會建議在這裏提高的優雅或受到質疑的代碼的可讀性，但你可以通過使用哈希存取模式，如進一步縮短：

def process(input) 
    commands = { 
    :q => Proc.new { puts "Goodbye" }, 
    :tweet => Proc.new { puts "tweeting" }, 
    :dm => Proc.new { puts "direct messaging"}, 
    :help => Proc.new { puts "helping"} 
    }[input.to_sym].call 
end 

Answer 3

使用Kernel#proc：

等同於Proc.new

def process(input) 
    commands = { 
    :q => proc { puts "Goodbye" }, 
    :tweet => proc { puts "tweeting" }, 
    :dm => proc { puts "direct messaging"}, 
    :help => proc { puts "helping"} 
    }[input.to_sym].call 
end