Class: HeadMusic::Style::Guides::CompositeGuide

Inherits:
Object
  • Object
show all
Defined in:
lib/head_music/style/guides/composite_guide.rb

Overview

Several guides graded together as one – a species is a melody guide and a harmony guide, and a student submits one line to be judged by both.

Stands in for a guide class wherever one is expected, the way Configured does, and is registered the same way: as an instance among the classes.

COMPOSES GRADES, NOT ITEMS. The tempting shape – one guide whose items are the union of its members’ – is wrong twice, and the second reason is the one that matters.

It cannot be built: a melody guide and its harmony partner both gate on MinimumNotes.with(3), GuideItem equality is by value, and Base.reject_duplicates refuses the union outright.

And it would undo the tier budgets. Those exist so that what a guide teaches does not thin out as inherited craft accumulates around it – see the comment in GuideAssessment. Merging first species puts nineteen primaries into a single phi^-1 budget and halves every taught rule’s share, which is that erosion arrived at from a different direction. The two levels also grade by different arithmetic on purpose: rules inside a rubric trade off against each other by weight, while a melody grade and a harmony grade must both hold.

So guide_items here is FOR DISPLAY, NOT FOR GRADING. It is deduplicated, and a fully graded composite therefore reports more item assessments than it has items – 27 against 26 for first species, because each member assesses the shared gate itself.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*guides) ⇒ CompositeGuide

Members resolved eagerly, for the reason Configured resolves its own: a bad member should raise here rather than mid-grading.

Nothing here may ask for key, display_name, or instruction. All three read Guide::REGISTRY, which does not exist yet while the registry’s second pass is constructing composites, and reaching for it fails on require.



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# File 'lib/head_music/style/guides/composite_guide.rb', line 39

def initialize(*guides)
  @guides = guides.flatten.freeze
  reject_bad_members!
  # Both memoize, and this object freezes: anything lazy must be resolved here
  # or its first reader raises FrozenError.
  guide_items
  categories
  freeze
end

Instance Attribute Details

#guides ⇒ Object (readonly)

Returns the value of attribute guides.



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# File 'lib/head_music/style/guides/composite_guide.rb', line 31

def guides
  @guides
end

Instance Method Details

#==(other) ⇒ Object Also known as: eql? 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 103

def ==(other)
  other.is_a?(self.class) && guides == other.guides
end

#assess(voice) ⇒ Object 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 49

def assess(voice)
  HeadMusic::Style::CompositeAssessment.new(self, voice)
end

#assess_items(voice) ⇒ Object

Every finding, flattened. Deliberately not what the grade is computed from – GuideAssessment refuses a composite, so this cannot silently become the grading path.



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# File 'lib/head_music/style/guides/composite_guide.rb', line 56

def assess_items(voice)
  guides.flat_map { |guide| guide.assess_items(voice) }
end

#categories ⇒ Object 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 83

def categories
  @categories ||= guides.flat_map(&:categories).uniq.freeze
end

#category ⇒ Object

A composite spans its members’ categories rather than claiming one. Consumers grouping the registry by category get a nil bucket; categories is the answer.



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# File 'lib/head_music/style/guides/composite_guide.rb', line 79

def category
  nil
end

#composite? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/style/guides/composite_guide.rb', line 73

def composite?
  true
end

#display_name ⇒ Object 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 93

def display_name
  key ? HeadMusic::Style::Guide.display_name_for(key) : guides.map(&:display_name).join(" + ")
end

#guide_items ⇒ Object 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 60

def guide_items
  @guide_items ||= HeadMusic::Style::Guides::Base::TIERS.flat_map { |tier| items_by_tier[tier] }.freeze
end

#hash ⇒ Object 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 108

def hash
  guides.hash
end

#inspect ⇒ Object 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 117

def inspect
  "#{self.class.name}(#{guides.map { |guide| guide.key || guide.name }.join(", ")})"
end

#instruction ⇒ Object

An unregistered composite borrows its members’ instructions rather than rendering a template no locale has.



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# File 'lib/head_music/style/guides/composite_guide.rb', line 99

def instruction
  key ? HeadMusic::Style::Guide.instruction_for(key) : guides.map(&:instruction).join(" ")
end

#items_by_tier ⇒ Object

Deduplicated within each tier rather than across the whole list, so a rule a guide gates on and another grades on stays two entries – the distinction Base.reject_duplicates exists to protect.



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# File 'lib/head_music/style/guides/composite_guide.rb', line 67

def items_by_tier
  @items_by_tier ||= HeadMusic::Style::Guides::Base::TIERS.to_h { |tier|
    [tier, guides.flat_map { |guide| guide.items_by_tier[tier] }.uniq.freeze]
  }.freeze
end

#key ⇒ Object

Reverse lookup, not derivation, matching Configured: an unregistered composite has no key rather than claiming one that resolves elsewhere.



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# File 'lib/head_music/style/guides/composite_guide.rb', line 89

def key
  HeadMusic::Style::Guide.key_for(self)
end

#name ⇒ Object Also known as: to_s 



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# File 'lib/head_music/style/guides/composite_guide.rb', line 112

def name
  guides.map(&:name).join(" + ")
end

#reject_bad_members! ⇒ Object (private)

Nesting is refused rather than left unspecified. At depth two, assessments would have to mean both the members that fitness divides by and the leaves a consumer walks, and those stop being the same list.

Raises:

  • (ArgumentError) 


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# File 'lib/head_music/style/guides/composite_guide.rb', line 126

def reject_bad_members!
  raise ArgumentError, "a composite grades more than one guide" if guides.length < 2

  nested = guides.select { |guide| guide.respond_to?(:composite?) && guide.composite? }
  return if nested.empty?

  raise ArgumentError, "a composite cannot hold another composite: #{nested.map(&:inspect).join(", ")}"
end