Merged updates from trunk into stable branch

[feedcatcher.git] / vendor / rails / activesupport / lib / active_support / core_ext / object / misc.rb

diff --git a/vendor/rails/activesupport/lib/active_support/core_ext/object/misc.rb b/vendor/rails/activesupport/lib/active_support/core_ext/object/misc.rb
new file mode 100644 (file)
index 0000000..4acdfa3
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+++ b/vendor/rails/activesupport/lib/active_support/core_ext/object/misc.rb
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+class Object
+  # Returns +value+ after yielding +value+ to the block. This simplifies the
+  # process of constructing an object, performing work on the object, and then
+  # returning the object from a method. It is a Ruby-ized realization of the K
+  # combinator, courtesy of Mikael Brockman.
+  #
+  # ==== Examples
+  #
+  #  # Without returning
+  #  def foo
+  #    values = []
+  #    values << "bar"
+  #    values << "baz"
+  #    return values
+  #  end
+  #
+  #  foo # => ['bar', 'baz']
+  #
+  #  # returning with a local variable
+  #  def foo
+  #    returning values = [] do
+  #      values << 'bar'
+  #      values << 'baz'
+  #    end
+  #  end
+  #
+  #  foo # => ['bar', 'baz']
+  #  
+  #  # returning with a block argument
+  #  def foo
+  #    returning [] do |values|
+  #      values << 'bar'
+  #      values << 'baz'
+  #    end
+  #  end
+  #  
+  #  foo # => ['bar', 'baz']
+  def returning(value)
+    yield(value)
+    value
+  end
+
+  # Yields <code>x</code> to the block, and then returns <code>x</code>.
+  # The primary purpose of this method is to "tap into" a method chain,
+  # in order to perform operations on intermediate results within the chain.
+  #
+  #   (1..10).tap { |x| puts "original: #{x.inspect}" }.to_a.
+  #     tap    { |x| puts "array: #{x.inspect}" }.
+  #     select { |x| x%2 == 0 }.
+  #     tap    { |x| puts "evens: #{x.inspect}" }.
+  #     map    { |x| x*x }.
+  #     tap    { |x| puts "squares: #{x.inspect}" }
+  def tap
+    yield self
+    self
+  end unless Object.respond_to?(:tap)
+
+  # An elegant way to factor duplication out of options passed to a series of
+  # method calls. Each method called in the block, with the block variable as
+  # the receiver, will have its options merged with the default +options+ hash
+  # provided. Each method called on the block variable must take an options
+  # hash as its final argument.
+  # 
+  #   with_options :order => 'created_at', :class_name => 'Comment' do |post|
+  #     post.has_many :comments, :conditions => ['approved = ?', true], :dependent => :delete_all
+  #     post.has_many :unapproved_comments, :conditions => ['approved = ?', false]
+  #     post.has_many :all_comments
+  #   end
+  #
+  # Can also be used with an explicit receiver:
+  #
+  #   map.with_options :controller => "people" do |people|
+  #     people.connect "/people",     :action => "index"
+  #     people.connect "/people/:id", :action => "show"
+  #   end
+  #
+  def with_options(options)
+    yield ActiveSupport::OptionMerger.new(self, options)
+  end
+  
+  # A duck-type assistant method. For example, Active Support extends Date
+  # to define an acts_like_date? method, and extends Time to define
+  # acts_like_time?. As a result, we can do "x.acts_like?(:time)" and
+  # "x.acts_like?(:date)" to do duck-type-safe comparisons, since classes that
+  # we want to act like Time simply need to define an acts_like_time? method.
+  def acts_like?(duck)
+    respond_to? "acts_like_#{duck}?"
+  end
+
+end