My bookmarks from Diigo 09/15/2009

• Eli Bendersky’s website

  tags: blog, tech, ruby, Eli Bendersky

• Closure & Block - ruby - Ruby - JavaEye论坛

  tags: ruby, block, closure

• Blocks and Closures in Ruby

  tags: ruby, block, closure

• Ruby中的Proc，Block的应用说明 - 机器人 - 帮我点击一下google的广告，好吗？赚钱上网 - JavaEye技术网站

  tags: ruby, proc, block

• thejavajar » Ruby Proc Fun

  tags: ruby, proc, block

• Eli Bendersky’s website » Blog Archive » Understanding Ruby blocks, Procs and methods

  tags: ruby, proc, block, tutorial

  • Procs play the role of functions in Ruby. It is more accurate to call them function objects, since like everything in Ruby they are objects. Such objects have a name in the folklore - functors. A functor is defined as an object to be invoked or called as if it were an ordinary function, usually with the same syntax, which is exactly what a Proc is.
  • Actually, there are two slight differences between lambda and Proc.new. First, argument checking. The Ruby documentation for lambda states: Equivalent to Proc.new, except the resulting Proc objects check the number of parameters passed when called.. Here is an example to demonstrate this:
  • lamb = lambda {|x, y| puts x + y}
    pnew = Proc.new {|x, y| puts x + y}
    
    # works fine, printing 6
    pnew.call(2, 4, 11)
    
    # throws an ArgumentError
    lamb.call(2, 4, 11)
  • Second, there is a difference in the way returns are handled from the Proc. A return from Proc.new returns from the enclosing method (acting just like a return from a block, more on this later):
  • def try_ret_procnew
    ret = Proc.new { return "Baaam" }
    ret.call
    "This is not reached"
    end
    
    # prints "Baaam"
    puts try_ret_procnew

  • While return from lambda acts more conventionally, returning to its caller:

    
    

  • def try_ret_lambda
    ret = lambda { return "Baaam" }
    ret.call
    "This is printed"
    end
    
    # prints "This is printed"
    puts try_ret_lambda
  • With this in light, I would recommend using lambda instead of Proc.new, unless the behavior of the latter is strictly required. In addition to being way cooler a whopping two characters shorter, its behavior is less surprising.

• Proc.new vs Lambda in Ruby by Sam

  tags: ruby, proc, Lambda

• Class: Proc

  tags: ruby, proc

Posted from Diigo. The rest of my favorite links are here.