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require 'tool/thread_local'
module Tool
# Mixin for easy method decorations.
#
# @example
# class Frank
# extend Tool::Decoration
# def self.get(path, &block)
# decorate(block) do |method|
# puts "mapping GET #{path} to #{method}"
# end
# end
# end
#
# # Output:
# # mapping GET /hi to __generated1
# # mapping GET / to index
# # mapping GET /index.php to index
# class MyApp < Frank
# get '/hi' do
# "Hello World"
# end
#
# get '/'; get '/index.php'
# def index
# "This is the index page."
# end
# end
module Decoration
module Initializer
# Make sure decorations list is initializsed upon instantiation.
# @!visibility private
def initialize(*)
setup_decorations
super
end
end
module Setup
# Make sure decorations list is initializsed if Decoration is included.
# @!visibility private
def included(object)
case object
when Class then object.send(:include, Initializer)
when Module then object.extend(Setup)
end
super
end
# Make sure decorations list is initializsed if Decoration extends an object.
# @!visibility private
def extended(object)
object.send(:setup_decorations)
super
end
end
extend Setup
# Set up a decoration.
#
# @param [Proc, UnboundMethod, nil] block used for defining a method right away
# @param [String, Symbol] name given to the generated method if block is given
# @yield callback called with method name once method is defined
# @yieldparam [Symbol] method name of the method that is to be decorated
def decorate(block = nil, name: "generated", &callback)
@decorations << callback
if block
alias_name = "__" << name.to_s.downcase.gsub(/[^a-z]+/, ?_) << ?1
alias_name = alias_name.succ while respond_to? alias_name, true
without_decorations { define_method(name, &block) }
alias_method(alias_name, name)
remove_method(name)
private(alias_name)
end
end
# Runs a given block without applying decorations defined outside of the block.
# Decorations defined before the block will still be registered after the block.
#
# @yield block to run without decorations
def without_decorations
@decorations.clear if was = @decorations.to_a.dup
yield
ensure
@decorations.replace(was) if was
end
def method_added(name)
@decorations.each { |d| d.call(name) }.clear
super
end
def setup_decorations
@decorations = Tool::ThreadLocal.new([])
end
private :method_added, :setup_decorations
private_constant :Initializer, :Setup
end
end
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