Adds class registry and factory

 - Abstract classes can extend Replicator::Replicable to make
   their descendants "replicable"

 - Concrete, "replicable" classes can self register under one or
   more keys by calling `replicates :symbol`

 - Multiple concrete, "replicable" classes can self register under
   the same key by calling `replicates :symbol`

 - Registered, "replicable" classes can be instantiated using the
   abstract parent's `.replicate(:symbol)` method

Co-authored-by: Fito von Zastrow <adolfovon@gmail.com>

Author: aridlehoover

CHANGELOG.md

@@ -9,4 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- Adds interface for building objects with Replicator
+- Abstract classes can extend Replicator::Replicable to make their descendants "replicable"
+- Concrete, "replicable" classes can self register under one or more keys by calling `replicates :symbol`
+- Multiple concrete, "replicable" classes can self register under the same key by calling `replicates :symbol`
+- Registered, "replicable" classes can be instantiated using the abstract parent's `.replicate(:symbol)` method

README.md

@@ -1,6 +1,6 @@
-# replicator
+# Replicator
 
-TODO: Write a description here
+Replicator is a class registry and factory.
 
 ## Installation
 
@@ -9,7 +9,7 @@ TODO: Write a description here
    ```yaml
    dependencies:
      replicator:
-       github: your-github-user/replicator
+       github: first-try-software/replicator
    ```
 
 2. Run `shards install`
@@ -18,22 +18,43 @@ TODO: Write a description here
 
 ```crystal
 require "replicator"
+
+abstract class Starship
+  extend Replicator::Replicable
+end
+
+class Enterprise < Starship
+  replicates :galaxy
+end
+
+class Cerritos < Starship
+  replicates :galaxy
+end
+
+Starship.replicate(:galaxy)  # => [#<Enterprise:0x1099ddd60>, #<Cerritos:0x1099ddd70>] : Array(Starship)
 ```
 
-TODO: Write usage instructions here
+## Roadmap
 
-## Development
+Replicator is ready to use in it's current state. The interfaces are unlikey to change. But, there will be new features added per our roadmap:
 
-TODO: Write development instructions here
+- [x] Abstract classes can extend Replicator::Replicable to make their descendants "replicable"
+- [x] Concrete, "replicable" classes can self register under one or more keys by calling `replicates :symbol`
+- [x] Multiple concrete, "replicable" classes can self register under the same key by calling `replicates :symbol`
+- [x] Registered, "replicable" classes can be instantiated using the abstract parent's `.replicate(:symbol)` method
+- [ ] Positional and named arguments may be passed when initializing "replicable" classes
+- [ ] A "replicable" class may register as the `default_replica` for an extended  abstract parent class, and will be instantiated when an unknown key is requested (good for the null object pattern)
+- [ ] A "replicable" class may register as `replicates_all` in which case, it is always instantiated and returned in addition to the classes that match a requested key
 
 ## Contributing
 
-1. Fork it (<https://github.com/your-github-user/replicator/fork>)
+1. Fork it (<https://github.com/first-try-software/replicator/fork>)
 2. Create your feature branch (`git checkout -b my-new-feature`)
 3. Commit your changes (`git commit -am 'Add some feature'`)
 4. Push to the branch (`git push origin my-new-feature`)
 5. Create a new Pull Request
 
 ## Contributors
 
-- [Alan Ridlehoover](https://github.com/your-github-user) - creator and maintainer
+- [Alan Ridlehoover](https://github.com/aridlehoover) - co-creator and maintainer
+- [Fito von Zastrow](https://github.com/Fito) - co-creator and maintainer

spec/replicator_spec.cr

@@ -1,12 +1,25 @@
 require "./spec_helper"
 
-class Galaxy; extend Replicator::Replicable; end
+abstract class Starship; extend Replicator::Replicable; end
+class Enterprise < Starship; replicates :galaxy; replicates :enterprise; end
+class Cerritos < Starship; replicates :galaxy; replicates :cerritos; end
 
 Spectator.describe Replicator do
-  describe ".build" do
-    it "returns an empty array when an unregistered class is provided" do
-      replicas = Galaxy.build(:iks_buruk)
-      expect(replicas.size).to eq(0)
-    end
+  it "returns an empty array when an unregistered class is requested" do
+    replicas = Starship.replicate(:iks_buruk)
+    expect(replicas.size).to eq(0)
+  end
+
+  it "allows a class to be registered under multiple keys" do
+    replicas = Starship.replicate(:enterprise)
+    expect(replicas.size).to eq(1)
+    expect(replicas.first).to be_a_kind_of(Enterprise)
+  end
+
+  it "allows multiple classes to be registred under the same key" do
+    replicas = Starship.replicate(:galaxy)
+    expect(replicas.size).to eq(2)
+    expect(replicas.first).to be_a_kind_of(Enterprise)
+    expect(replicas.last).to be_a_kind_of(Cerritos)
   end
 end

src/replicator/registry.cr

@@ -0,0 +1,30 @@
+module Replicator
+  class Registry(K, V)
+    private getter :registry
+
+    def initialize
+      @registry = Hash(K, Set(V)).new
+    end
+
+    def add(key : K, value)
+      setup_registry_for(key)
+      items_for(key).add(value)
+    end
+
+    def get(key : K)
+      items_for(key)
+    end
+
+    private def setup_registry_for(key)
+      registry[key] ||= Set(V).new
+    end
+
+    private def items_for(key)
+      registered?(key) ? registry[key] : Set(V).new
+    end
+
+    private def registered?(key : K)
+      registry.keys.includes?(key)
+    end
+  end
+end

src/replicator/replicable.cr

@@ -1,7 +1,21 @@
+require "./registry"
+
 module Replicator
   module Replicable
-    def build(key)
-      Array(String).new
+    macro extended
+      def self.replicates(key)
+        {{@type}}.__replicable_registry.add(key, self)
+      end
+
+      def self.replicate(key)
+        {{@type}}.__replicable_registry
+          .get(key)
+          .map { |klass| klass.new }
+      end
+
+      protected def self.__replicable_registry
+        @@__replicable_registry ||= Replicator::Registry(Symbol, {{@type.class}}).new
+      end
     end
   end
 end