https://github.com/zverok/delegates
delegate :methods, to: :target, extracted from ActiveSupport
https://github.com/zverok/delegates
delegate ruby
Last synced: 9 months ago
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delegate :methods, to: :target, extracted from ActiveSupport
- Host: GitHub
- URL: https://github.com/zverok/delegates
- Owner: zverok
- Created: 2020-06-09T17:22:19.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2020-06-13T16:42:01.000Z (over 5 years ago)
- Last Synced: 2025-04-17T13:57:36.786Z (10 months ago)
- Topics: delegate, ruby
- Language: Ruby
- Size: 64.5 KB
- Stars: 32
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Delegates
[](http://badge.fury.io/rb/delegates)
This gem is just an extraction of the handy `delegate :method1, :method2, method3, to: :receiver` from ActiveSupport. It seems to be seriously superior to stdlib's [Forwardable](https://ruby-doc.org/stdlib-2.7.1/libdoc/forwardable/rdoc/Forwardable.html), and sometimes I want it in contexts when ActiveSupport and monkey-patching is undesireable.
Usage:
```
gem install delegates
```
(or add `gem 'delegates'` to your `Gemfile`).
Then:
```ruby
class Employee < Struct.new(:name, :department, :address)
# ...
extend Delegates
delegate :city, :street, to: :address
# ...
end
employee = Employee.new(name, department, address)
employee.city # will call employee.address.city
```
`to:` can be anything evaluatable from inside the class: `:`, `:@`, `'chain.of.calls'` etc.; special names requiring `self` (like `class` method) handled gracefully with just `delegate ..., to: :class`. New methods are defined with `eval`-ing strings, so they are as fast as if manually written.
Supported options examples (all that ActiveSupport's `Module#delegate` supports):
```ruby
delegate :city, to: :address, prefix: true # defined method would be address_city
delegate :city, to: :address, prefix: :adrs # defined method would be adrs_city
delegate :city, to: :address, private: true # defined method would be private
delegate :city, to: :address, allow_nil: true
```
The latter option will handle the `employee.city` call when `employee.address` is `nil` by returning `nil`; otherwise (by default) informative `DelegationError` is raised.
## Credits
99.99% of credits should go to Rails users and contributors, who found and and handled miriads of realistic edge cases. I just copied the code (and groomed it a bit for closer to my own style).