Add: Concept Of A Projector

Why This Change Is Necessary
========================================================================

Currently the `Progress` class is doing too much.  It's both in charge
of keeping track of the progress but also in understanding how quickly
each item of progress is being executed.

We need to split the objects up so that each object is responsible for
its own job.

What These Changes Do To Address the Issue
========================================================================

Introduce the concept of a "projector".

Caveats
------------------------------------------------------------------------

Currently this is simply the calculator but will be fleshed out in later
commits.

Side Effects Caused By This Change
========================================================================

None expected.

Author: jfelchner

lib/ruby-progressbar/base.rb

@@ -1,5 +1,6 @@
 require 'forwardable'
 
+require 'ruby-progressbar/calculators/smoothed_average'
 require 'ruby-progressbar/components/bar'
 require 'ruby-progressbar/components/percentage'
 require 'ruby-progressbar/components/rate'
@@ -31,10 +32,12 @@ def initialize(options = {}) # rubocop:disable Metrics/AbcSize
     self.finished     = false
 
     self.timer        = Timer.new(options)
-    self.progressable = Progress.new(options)
+    self.projector    = Calculators::SmoothedAverage.new(:strength => options[:smoothing])
+    self.progressable = Progress.new(options.merge(:projector => projector))
 
-    options = options.merge(:progress => progressable,
-                            :timer    => timer)
+    options = options.merge(:progress  => progressable,
+                            :projector => projector,
+                            :timer     => timer)
 
     self.title_component      = Components::Title.new(options)
     self.bar_component        = Components::Bar.new(options)
@@ -174,6 +177,7 @@ def format=(other)
   protected
 
   attr_accessor :output,
+                :projector,
                 :timer,
                 :progressable,
                 :title_component,

lib/ruby-progressbar/calculators/smoothed_average.rb

@@ -1,8 +1,24 @@
 class   ProgressBar
 module  Calculators
 class   SmoothedAverage
-  def self.calculate(current_average, new_value_to_average, rate)
-    (new_value_to_average * (1.0 - rate)) + (current_average * rate)
+  DEFAULT_STRENGTH = 0.1
+
+  attr_accessor :strength
+
+  def initialize(options = {})
+    self.strength = options[:strength] || DEFAULT_STRENGTH
+  end
+
+  def calculate(current_projection, new_value)
+    self.class.calculate(
+      current_projection,
+      new_value,
+      strength
+    )
+  end
+
+  def self.calculate(current_projection, new_value, rate)
+    (new_value * (1.0 - rate)) + (current_projection * rate)
   end
 end
 end

lib/ruby-progressbar/progress.rb

@@ -1,33 +1,20 @@
 require 'ruby-progressbar/errors/invalid_progress_error'
-require 'ruby-progressbar/calculators/smoothed_average'
 
 class   ProgressBar
 class   Progress
-  DEFAULT_TOTAL                      = 100
-  DEFAULT_BEGINNING_POSITION         = 0
-  DEFAULT_RUNNING_AVERAGE_RATE       = 0.1
-  DEFAULT_RUNNING_AVERAGE_CALCULATOR = ProgressBar::Calculators::SmoothedAverage
-
-  RUNNING_AVERAGE_CALCULATOR_MAP     = {
-    'smoothing' => ProgressBar::Calculators::SmoothedAverage
-  }.freeze
+  DEFAULT_TOTAL              = 100
+  DEFAULT_BEGINNING_POSITION = 0
 
   attr_reader               :total,
                             :progress
 
   attr_accessor             :starting_position,
                             :running_average,
-                            :running_average_calculator,
-                            :running_average_rate
+                            :running_average_calculator
 
   def initialize(options = {})
     self.total                      = options.fetch(:total, DEFAULT_TOTAL)
-    self.running_average_rate       = options[:smoothing] ||
-                                      options[:running_average_rate] ||
-                                      DEFAULT_RUNNING_AVERAGE_RATE
-    self.running_average_calculator = RUNNING_AVERAGE_CALCULATOR_MAP.
-                                        fetch(options[:running_average_calculator],
-                                              DEFAULT_RUNNING_AVERAGE_CALCULATOR)
+    self.running_average_calculator = options[:projector]
 
     start :at => DEFAULT_BEGINNING_POSITION
   end
@@ -79,8 +66,7 @@ def progress=(new_progress)
     @progress = new_progress
 
     self.running_average = running_average_calculator.calculate(running_average,
-                                                                absolute,
-                                                                running_average_rate)
+                                                                absolute)
   end
 
   def total=(new_total)

spec/lib/ruby-progressbar/calculators/smoothed_average_spec.rb

@@ -4,15 +4,27 @@
 class    ProgressBar
 module   Calculators
 describe SmoothedAverage do
-  it 'can properly calculate a running average' do
-    first_average = SmoothedAverage.calculate(4.5,  12,  0.1)
-    expect(first_average).to be_within(0.001).of 11.25
+  it 'can properly calculate a projector' do
+    first_projection = SmoothedAverage.calculate(4.5,  12,  0.1)
+    expect(first_projection).to be_within(0.001).of 11.25
 
-    second_average = SmoothedAverage.calculate(8.2,  51,  0.7)
-    expect(second_average).to be_within(0.001).of 21.04
+    second_projection = SmoothedAverage.calculate(8.2,  51,  0.7)
+    expect(second_projection).to be_within(0.001).of 21.04
 
-    third_average = SmoothedAverage.calculate(41.8, 100, 0.59)
-    expect(third_average).to be_within(0.001).of 65.662
+    third_projection = SmoothedAverage.calculate(41.8, 100, 0.59)
+    expect(third_projection).to be_within(0.001).of 65.662
+  end
+
+  describe '#strength' do
+    it 'allows the default strength to be overridden' do
+      projector = SmoothedAverage.new(:strength => 0.3)
+
+      expect(projector.strength).to be 0.3
+    end
+
+    it 'has a default strength' do
+      expect(SmoothedAverage.new.strength).to be 0.1
+    end
   end
 end
 end