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Contents
require 'tap/support/dependency'
module Tap
module Support
# Dependencies tracks Executable dependencies and results, and provides
# for thread-safe resolution of dependencies.
class Dependencies < Monitor
# Initializes a new Dependencies
def initialize
super
@resolve_stack = []
end
# Thread-safe registration of instance as a dependency. During
# registration, instance is extended with the Dependency module.
# Returns self.
def register(instance)
synchronize do
unless instance.kind_of?(Dependency)
instance.extend Dependency
end
end
self
end
# Thread-safe resolution of the instance. Resolve checks for
# circular dependencies, then yields control to the block,
# which is responsible for the actual resolution.
def resolve(instance)
synchronize do
if @resolve_stack.include?(instance)
raise CircularDependencyError.new(@resolve_stack)
end
# mark the results at the index to prevent
# infinite loops with circular dependencies
@resolve_stack.push instance
yield()
@resolve_stack.pop
end
self
end
# Raised when Dependencies#resolve detects a circular dependency.
class CircularDependencyError < StandardError
def initialize(resolve_stack)
super "circular dependency: [#{resolve_stack.join(', ')}]"
end
end
end
end
end
Version data entries
12 entries across 12 versions & 2 rubygems