Oscillo

Based off of functional reactive programming, oscillo gives you a signal that represents a value changing over time. You can manipulate signals and combine them together in various ways.

• source: https://github.com/evant/oscillo
• documentation: http://rubydoc.info/github/evant/oscillo/frames

Add this line to your application's Gemfile:

gem 'oscillo'

And then execute:

$ bundle

Or install it yourself as:

$ gem install oscillo

Creating a signal is as simple as

s = Oscillo::Signal.new

You modify the value of the signal with s << :value and you get the current value of the signal with s.value, or s.val if you want to save a couple of letters.

If you want to give a signal a starting value, you just pass it to the constructor.

s = Oscillo::Signal.new(0)

If you pass another signal as an argument to new, the signal's value will follow the other one.

a = Oscillo::Signal.new
b = Oscillo::Signal.new(a)

a << :value
b.val #=> :value

You can pass a block to new to modify how the new signal follows the old.

a = Oscillo::Signal.new(0)
b = Oscillo::Signal.new(a) { |v| v * 2 }

a << 3
b.val #=> 6

You can also follow multiple signals at once. The new signal will change if any of the signal that you follow changes.

a = Oscillo::Signal.new(0)
b = Oscillo::Signal.new(0)
c = Oscillo::Signal.new(a, b) { |v1, v2| v1 + v2 }

a << 2
c.val #=> 2
b << 3
c.val #=> 5

Eventually, you want to perform some action when the value of the signal changes. To do this, register a callback with the #on_change method. You can also use #each if you want to think of it as an Enumerable.

s = Oscillo::Signal.new
s.on_change { |v| puts "The new value is: #{v}" }
s << 1
#=> "The new value is: 1

The last argument given to the block passed to new is the signal itself. This is so you utilize other methods to query the signal and modify it's changed value.

{Oscillo::Signal#abort} aborts the new value change, keeping the old one.

a = Oscillo::Signal.new
b = Oscillo::Signal.new(a) { |v, s| s.abort if v == :bad; v }

a << :good
b.val #=> :good
a << :bad
b.val #=> :bad

{Oscillo::Signal#source} gives the original signal that caused the cascade of changes. This is useful if you are following multiple signals and want to know which one actually changed.

a = Oscillo::Signal.new
b = Oscillo::Signal.new
c = Oscillo::Signal.new(a, b) do |v1, v2, s|
  "The last change was to #{s.source.val}"
end

a << 1
c.val #=> "The last change was to 1"
b << 2
c.val #=> "The last change was to 2"

You can combine signals together in different ways. For example, {Oscillo::Combine.either} updates the new signal to the value of whichever was the last signal to change.

a = Oscillo::Signal.new
b = Oscillo::Signal.new
c = Oscillo::Combine.either(a, b)
a << "a changed"
c.val #=> "a changed"
b << "b changed"
c.val #=> "b changed"

See {Oscillo::Combine} for all combination methods.

A signal can thought of a sequence of values over time. Therefore, {Oscillo::Signal} implements a large number of Enumerable's methods. For example,

a = Oscillo::Signal.new(0)
b = a.map { |v| v ** 2 }
a << 3
b.val #=> 9

See {Oscillo::Enumerable} for all the methods implemented.

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