https://github.com/ruby/singleton
The Singleton module implements the Singleton pattern.
https://github.com/ruby/singleton
ruby
Last synced: about 1 month ago
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The Singleton module implements the Singleton pattern.
- Host: GitHub
- URL: https://github.com/ruby/singleton
- Owner: ruby
- License: other
- Created: 2019-08-06T03:48:37.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2025-04-29T23:53:35.000Z (about 2 months ago)
- Last Synced: 2025-04-30T00:30:38.615Z (about 2 months ago)
- Topics: ruby
- Language: Ruby
- Homepage:
- Size: 104 KB
- Stars: 29
- Watchers: 32
- Forks: 8
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: COPYING
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README
# Singleton
The Singleton module implements the Singleton pattern.
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'singleton'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install singleton
## Usage
To use Singleton, include the module in your class.
```ruby
class Klass
include Singleton
# ...
end
```
This ensures that only one instance of Klass can be created.
```ruby
a,b = Klass.instance, Klass.instance
a == b
# => true
Klass.new
# => NoMethodError - new is private ...
```
The instance is created at upon the first call of Klass.instance().
```ruby
class OtherKlass
include Singleton
# ...
end
ObjectSpace.each_object(OtherKlass){}
# => 0
OtherKlass.instance
ObjectSpace.each_object(OtherKlass){}
# => 1
```
This behavior is preserved under inheritance and cloning.
## Development
After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/ruby/singleton.