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Add Object#acts_like? and Time#acts_like_time? and Date#acts_like_dat…

…e? to facilitate duck-typing

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5951 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
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1 parent 8368e16 commit f28eef9a272fd9280416fd8c0984f616ffe102fe @jamis jamis committed Jan 15, 2007
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@@ -1,5 +1,7 @@
*SVN*
+* Add Object#acts_like? and Time#acts_like_time? and Date#acts_like_date? to facilitate duck-typing. [Jamis Buck]
+
* Make 1.months and friends accurate by introducing a Duration class. #6835 [eventualbuddha]
* Document Inflector.ordinalize and merge docs from String inflections. #7023 [smeade]
@@ -1,8 +1,10 @@
require 'date'
+require File.dirname(__FILE__) + '/date/behavior'
require File.dirname(__FILE__) + '/date/calculations'
require File.dirname(__FILE__) + '/date/conversions'
class Date#:nodoc:
+ include ActiveSupport::CoreExtensions::Date::Behavior
include ActiveSupport::CoreExtensions::Date::Calculations
include ActiveSupport::CoreExtensions::Date::Conversions
end
@@ -0,0 +1,13 @@
+module ActiveSupport #:nodoc:
+ module CoreExtensions #:nodoc:
+ module Date #:nodoc:
+ module Behavior
+ # Enable more predictable duck-typing on Date-like classes. See
+ # Object#acts_like?.
+ def acts_like_date?
+ true
+ end
+ end
+ end
+ end
+end
@@ -0,0 +1,5 @@
+require "#{File.dirname(__FILE__)}/time/behavior"
+
+class DateTime
+ include ActiveSupport::CoreExtensions::Time::Behavior
+end
@@ -31,4 +31,13 @@ def with_options(options)
def to_json
ActiveSupport::JSON.encode(self)
end
+
+ # A duck-type assistant method. For example, ActiveSupport 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
@@ -1,7 +1,9 @@
+require File.dirname(__FILE__) + '/time/behavior'
require File.dirname(__FILE__) + '/time/calculations'
require File.dirname(__FILE__) + '/time/conversions'
class Time#:nodoc:
+ include ActiveSupport::CoreExtensions::Time::Behavior
include ActiveSupport::CoreExtensions::Time::Calculations
include ActiveSupport::CoreExtensions::Time::Conversions
end
@@ -0,0 +1,13 @@
+module ActiveSupport #:nodoc:
+ module CoreExtensions #:nodoc:
+ module Time #:nodoc:
+ module Behavior
+ # Enable more predictable duck-typing on Time-like classes. See
+ # Object#acts_like?.
+ def acts_like_time?
+ true
+ end
+ end
+ end
+ end
+end
@@ -96,6 +96,34 @@ def test_extend_with_included_modules_from
assert object.respond_to?(:baz)
end
+ class DuckTime
+ def acts_like_time?
+ true
+ end
+ end
+
+ def test_duck_typing
+ object = Object.new
+ time = Time.now
+ date = Date.today
+ dt = DateTime.new
+ duck = DuckTime.new
+
+ assert !object.acts_like?(:time)
+ assert !object.acts_like?(:date)
+
+ assert time.acts_like?(:time)
+ assert !time.acts_like?(:date)
+
+ assert !date.acts_like?(:time)
+ assert date.acts_like?(:date)
+
+ assert dt.acts_like?(:time)
+ assert dt.acts_like?(:date)
+
+ assert duck.acts_like?(:time)
+ assert !duck.acts_like?(:date)
+ end
end
class ObjectInstanceVariableTest < Test::Unit::TestCase

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