Wrapit

Having nils floating around in your app can be a very bad thing. Nils cause errors and can sometimes be hard to track down if they happen far away from where the nil was introduced. Thankfully the wrapped gem helps mitigate this.

Wrapit extends wrapped by allowing you to easily define attributes in a class that should be wrapped, or wrap methods that have already been defined. In this way if you do have an unexpected nil somewhere you can easily handle it without causing an app breaking error.

Installation

Add this line to your application's Gemfile:

gem 'wrapit'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install wrapit

Usage

attr_wrappable

So lets say we want to create some setters and getters for a class that come all wrapped and ready to go.

class Foo
  include Wrapit::AttrWrappable

  attr_wrappable :test_attr
end

foo = Foo.new

foo.test_attr = "bar"
foo.test_attr => #<Present:0x0000010ad6fc80 @value="bar">
foo.test_attr.unwrap => "bar"

foo.test_attr = nil
foo.test_attr => #<Blank:0x0000010d3064f8>
foo.test_attr.unwrap => IndexError: Blank has no value
foo.test_attr.unwrap_or("bar") => "bar"

In addition to wrapping up the attribute readers, attr_wrappable creates _naked attribute writers:

foo.test_attr_naked => nil
foo.test_attr_naked = "bar"
foo.test_attr_naked => "bar"

# test_attr= is just an alias to test_attr_naked=
foo.test_attr = "foo"
foo.test_attr_naked = "foo"

method_wrappable

Now lets say you have a method you have inherited from a superclass you want to wrap.

class Foo
  def test_method
    "bar"
  end
end

class Bar < Foo
  include Wrapit::MethodWrappable

  method_wrappable :test_method
end

bar = Bar.new

bar.test_method => #<Present:0x0000010ad6fc80 @value="bar">
bar.test_method.unwrap => "bar"
bar.test_method_naked => "bar"

And that's it!

Further Reading

For more info on what you can do with a wrapped value have a look at the wrapped gem.

Limitations

At the moment method_wrappable is only usable on methods defined in a superclass and that take no arguments.

TODO

1. Add option to attr_wrappable to skip creating attribute writers.
2. Make method_wrappable work with methods that take arguments.
3. Look into method_wrappable working better in scenarios where we want to wrap a dynamic method. ie. ActiveRecord attributes.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request