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https://github.com/alindeman/null_object
Dead simple library to create null objects (objects that respond to all messages)
https://github.com/alindeman/null_object
Last synced: 2 months ago
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Dead simple library to create null objects (objects that respond to all messages)
- Host: GitHub
- URL: https://github.com/alindeman/null_object
- Owner: alindeman
- License: mit
- Created: 2012-05-10T18:29:34.000Z (over 12 years ago)
- Default Branch: master
- Last Pushed: 2012-05-18T14:44:49.000Z (over 12 years ago)
- Last Synced: 2024-10-13T17:51:37.063Z (2 months ago)
- Language: Ruby
- Size: 113 KB
- Stars: 2
- Watchers: 4
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# NullObject
[](http://travis-ci.org/alindeman/null_object)
Dead simple library to create null objects (objects that respond to all
messages)
## Requirements
* MRI 1.9, JRuby in 1.9 mode (`JRUBY_OPTS=--1.9`), Rubinius in 1.9 mode
(`RBXOPT=-X19`)
## Why?
Imagine that sometimes your code uses a [statsd](https://github.com/etsy/statsd)
client to instrument itself. But only sometimes.
If you used `nil` to represent the case where the statsd client isn't configured,
you end up writing code like this ... which sucks:
```ruby
statsd.increment("foo") if statsd
```
And how to you deal with timers? I have no idea
```ruby
# statsd might be nil, ugh!
statsd.time("foo") { ... }
```
But if your `statsd` were either a real `Statsd` client **or a `NullObject`**,
the problems go away:
```
statsd = NullObject.new { |&block| block.call if block }
statsd.increment("foo") # no need for a conditional; it's a no-op
statsd.time("foo") { ... } # yields to the block, but otherwise a no-op
```
## Usage
Respond to ALL the things:
```ruby
obj = NullObject.new
obj.foo # => obj
obj.bar # => obj
obj.foo.bar # => obj
```
Yield ALL the things:
```ruby
obj = NullObject.new { |&block| block.call if block }
obj.foo { puts "bar" } # outputs "bar"
```
Respond to SOME of the things:
```ruby
obj = NullObject.new(:foo, :bar)
obj.foo # => obj
obj.bar # => obj
obj.baz # raises NoMethodError
```
Respond to SOME of the things with CERTAIN return values:
```ruby
obj = NullObject.new(:foo => :bar)
obj.foo # => :bar
obj.baz # raises NoMethodError
```
Respond to ALL of the things with a CERTAIN return value:
```ruby
obj = NullObject.new { "foo" }
obj.foo # => "foo"
obj.bar # => "foo"
```
Respond to ALL of the things with nil:
```ruby
obj = NullObject.new { nil }
obj.foo # => nil
```
## Contributing
1. Fork it
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Added some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create new Pull Request