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[](http://rubygems.org/gems/ddmemoize)
[](http://rubygems.org/gems/ddmemoize)
[](https://travis-ci.org/ddfreyne/ddmemoize)
[](https://codeclimate.com/github/ddfreyne/ddmemoize)
[](https://codecov.io/gh/ddfreyne/ddmemoize)
# DDMemoize
_DDMemoize_ adds support for memoizing Ruby functions.
For example, the following Fibonacci implementation runs quickly (in O(n) rather than in O(2^n)):
```ruby
class FibFast
DDMemoize.activate(self)
memoized def run(n)
if n == 0
0
elsif n == 1
1
else
run(n - 1) + run(n - 2)
end
end
end
```
Features:
* Supports memoizing functions on frozen objects
* Releases memoized values when needed in order to reduce memory pressure
* Optionally records metrics
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'ddmemoize'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install ddmemoize
## Usage
First, require `ddmemoize` and enable it using `DDMemoize.activate`:
```ruby
require 'ddmemoize'
class FibFast
DDMemoize.activate(self)
# …
end
```
To memoize a function, call `memoize` with the name of the function:
```ruby
def run(n)
# …
end
memoize :run
```
Alternatively, prepend `memoized` to the function definition:
```ruby
memoized def run(n)
# …
end
```
Do not memoize functions that depend on mutable state.
### Metrics
To activate metrics, call `DDMemoize.enable_metrics` after requiring `ddmemoize`.
To print the collected metrics, call `DDMemoize.print_metrics`:
```ruby
DDMemoize.print_metrics
```
```
memoization │ hit miss %
────────────┼───────────────────
FibFast#fib │ 998 1001 49.9%
```
## Development
Install dependencies:
$ bundle
Run tests:
$ bundle exec rake
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/ddfreyne/ddmemoize. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.
## License
The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).
## Code of Conduct
Everyone interacting in the DDMemoize project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/ddfreyne/ddmemoize/blob/master/CODE_OF_CONDUCT.md).
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