Pass multiple blocks to a Ruby method
Ruby
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Failed to load latest commit information.
lib
spec
.gitignore
.travis.yml
CHANGELOG.rdoc
Gemfile
MIT-LICENSE.txt
README.rdoc
Rakefile
multi_block.gemspec

README.rdoc

MultiBlock

MultiBlock is a mini framework for passing multiple blocks to methods. It uses named procs to accomplish this with a simple syntax. The receiving method can either yield all blocks, or just call specific ones, identified by order or name.

Setup

Add to Gemfile:

gem 'multi_block'

Usage

Defining methods that use multiple blocks

The first argument given to yield always defines the desired block(s). The other arguments get directly passed to the block(s):

yield                                            # calls all given procs without args
yield :success                                   # calls :success proc without args
yield :success, "Code Brawl!"                    # calls :success proc with message
yield 1                                          # calls first proc (:success in this case)
yield [:success, :bonus]                         # calls :success and :bonus without args
yield [:success, :bonus], "Code Brawl!"          # calls both procs with same arg
yield success: "Code Brawl!",                    # calls each keyed proc,
      error:   [500, "Internal Brawl Error"]     #       values are the args

Calling methods with multiple blocks

Consider these two example methods:

# calls the :success block if everything worked well
def ajax
  yield rand(6) != 0 ? :success : :error
end

# calls the n-th block
def dice
  random_number = rand(6)
  yield random_number, random_number + 1
end

Multiple blocks can be passed using blocks:

ajax &blocks[
  proc.success{ puts "Yeah!"    },
  proc.error  { puts "Error..." },
]

The dice method could, for example, be called in this way:

dice &blocks[
  proc{ ":(" },
  proc{ ":/" },
  proc{ ":O" },
  proc{ ":b" },
  proc{ ":P" },
  proc{ rand(42) != 0 ? ":)"  : ":D"},
]

Bonus sugar: Array extension

If you like the slim &to_proc operator, you can further optimize the syntax by activating the core extension for array:

require 'multi_block/array'

Now you do not need the blocks helper anymore. Instead just do:

do_something, some_argument, &[
  proc.easy_way{
    # do it the easy way
  },
  proc.complex_way{
    # use complex heuristics, etc.
  },
]

MIT License

See the original gist: gist.github.com/4b2f5fd0b45118e46d0f