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