Mayhaps Gem Version

Mayhaps (maybe) call Ruby methods.

Usage

Mayhaps allows you to call methods on objects that may or may not be nil.

First, install the gem or add it to your Gemfile:

gem "mayhaps", "~> 0.3.0"

Next, require it:

require 'mayhaps'

On the surface

Mayhaps adds a maybe method to all objects that allows you to call methods on the object regardless of whether or not it is nil. It does this by wrapping the object in a Maybe object, more specifically a Nothing object for nil or a Just object for anything else. To unwrap the value, use unary + on the Maybe object.

Examples

hash = {:foo => " foo "}

hash[:foo].maybe.upcase #=> #<Just " FOO ">
hash[:bar].maybe.upcase #=> #<Nothing>

+hash[:foo].maybe.upcase #=> " FOO "
+hash[:bar].maybe.upcase #=> nil

+hash[:foo].maybe.upcase.strip #=> "FOO"
+hash[:bar].maybe.upcase.strip #=> nil

# Without Mayhaps
if customer && customer.order && customer.order.id == some_id
  # Do something with customer
end

# With Mayhaps
require 'mayhaps'

if +customer.maybe.order.id == some_id
  # Do something with customer
end

The nitty gritty

Just and Nothing both inherit from BasicObject rather than Object in order to allow the maximum number of methods to fall through to the wrapped object. This includes methods like class and is_a?, therefore the === method of the Maybe classes should be used to check if an object is wrapped in a Maybe.

Maybe === :a.maybe #=> true
Just === :a.maybe #=> true
Maybe === nil.maybe #=> true
Nothing === nil.maybe #=> true

The methods that will be called on the Maybe object itself and not the wrapped object are:

  • +@
  • method_missing
  • inspect
  • maybe
  • _dump
  • ==
  • equal?
  • !
  • !=
  • instance_eval
  • instance_exec
  • __send__
  • __id__

_dump is a method added by the Singleton module, which Nothing includes.

The maybe method defined on Maybe allows for nested Maybe objects.

The maybe method should be used to wrap objects in Maybe objects, but they can also be created directly. Since Nothing is a Singleton, its instance can be accessed using Nothing.instance. A Just object can be created by calling Just.new. If the object passed to Just.new is nil, an ArgumentError will be raised.

License

Copyright © 2013, Curtis McEnroe [email protected]

Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.