Class: Inject::Injector

Inherits:
Object
  • Object
show all
Defined in:
lib/inject.rb

Constant Summary collapse

NULL_SOURCE = 
Proc.new {}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*sources) ⇒ Injector

Returns a new instance of Injector.



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# File 'lib/inject.rb', line 12

def initialize(*sources)
  @known = {}
  sources.each { |source| add_source(source) }
end

Instance Attribute Details

#known ⇒ Object (readonly)

Returns the value of attribute known.



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# File 'lib/inject.rb', line 10

def known
  @known
end

Instance Method Details

#add_source(source) ⇒ Object 



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# File 'lib/inject.rb', line 23

def add_source(source)
  extract_injections(source).each do |name|
    prevent_collisions(name)
    known[name] = source.method(name)
  end
end

#call(target, name) ⇒ Object 



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# File 'lib/inject.rb', line 17

def call(target, name)
  method = target.method(name)
  args   = resolve(method.parameters)
  method.call(*args)
end

#extract_injections(source) ⇒ Object 



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# File 'lib/inject.rb', line 30

def extract_injections(source)
  if source.respond_to?(:injections)
    source.injections
  else
    source.class.instance_methods(false)
  end
end

#fetch(type, name) ⇒ Object 



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# File 'lib/inject.rb', line 49

def fetch(type, name)
  known.fetch(name) do |key|
    prevent_unkown_required_args(type, name)
    NULL_SOURCE
  end
end

#ignore?(type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/inject.rb', line 44

def ignore?(type)
  @ignored_types ||= [:block, :rest]
  @ignored_types.include?(type)
end

#prevent_collisions(name) ⇒ Object

Raises:



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# File 'lib/inject.rb', line 61

def prevent_collisions(name)
  return unless known.key?(name)
  raise Conflict.new("The :#{name} method is defined more than once.")
end

#prevent_unkown_required_args(type, name) ⇒ Object

Raises:



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# File 'lib/inject.rb', line 56

def prevent_unkown_required_args(type, name)
  return unless type == :req
  raise UnknownArg.new("Don't know how to inject :#{name}")
end

#resolve(parameters) ⇒ Object 



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# File 'lib/inject.rb', line 38

def resolve(parameters)
  parameters.map do |type, name|
    fetch(type, name).call unless ignore?(type)
  end.compact
end