motion-set

Implementation of Ruby set module

This gems implements Set class from set standard library of Ruby 1.9.3. See Ruby 1.9.3 Set API documentation

Installation

Add this line to your application's Gemfile:

gem 'motion-set'

And then execute:

$ bundle

Or install it yourself as:

$ gem install motion-set

Implementation details

No require

RubyMotion does not support require. Instead, when you install this gem, Set class will be globally available.

Set is NSMutableSet

Set is implemented as an alias to NSMutableSet, which it turn is extended to accomodate all Ruby set methods. This is similar to how other RubyMotion data types (like Array) are implemented.

Advantages of this approach are:

1. Interoperability with native APIs:
   • You can pass Set objects to APIs expecting NSSet or NSMutableSet.
   • Whenever a native API returns an NSMutableSet you can treat it as Ruby set.
2. There's no performance penalty, because there is no unnecessary indirection.

However, there are some things you need to note:

No nil in sets

NSMutableSet does not support adding nil object, which applies to your Ruby sets.

This could fail in subtle ways, for example if you try to call #map! with a block which returns nil.

This could have been avoided if the implementation checked when nil is added, and instead stored a private singelton sentinel fake nil object, which would be converted back to nil when necessary. However, this would create a challenge for interoperability with native APIs: what should this object represent in Objective-C world?

If you have opinion on this, you are welcom to comment on this issue.

No #divide method

#divide method is not implemented. You are welcome to contribute.

No SortedSet

SortedSet is not implemented. You are welcome to contribute.

No Android support

There is no Android support, but you are welcome to contribute.

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