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adds test coverage for edge-cases of Array.wrap, and better documenta…

…tion for how it differs from Kernel#Array
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1 parent 5d3e8ee commit e17e08efef68e9865cfbd5c0155b3d9734339192 @fxn fxn committed Jul 28, 2010
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13 activesupport/lib/active_support/core_ext/array/wrap.rb
@@ -1,9 +1,14 @@
class Array
- # Wraps the object in an Array unless it's an Array. Converts the
- # object to an Array using #to_ary if it implements that.
+ # <tt>Array.wrap</tt> is like <tt>Kernel#Array</tt> except:
#
- # It differs with Array() in that it does not call +to_a+ on
- # the argument:
+ # * If the argument responds to +to_ary+ the method is invoked. <tt>Kernel#Array</tt>
+ # moves on to try +to_a+ if the returned value is +nil+, but <tt>Arraw.wrap</tt> returns
+ # such a +nil+ right away.
+ # * If the returned value from +to_ary+ is neither +nil+ nor an +Array+ object, <tt>Kernel#Array</tt>
+ # raises an exception, while <tt>Array.wrap</tt> does not, it just returns the value.
+ # * It does not call +to_a+ on the argument, though special-cases +nil+ to return an empty array.
+ #
+ # The last point is particularly worth comparing for some enumerables:
#
# Array(:foo => :bar) # => [[:foo, :bar]]
# Array.wrap(:foo => :bar) # => [{:foo => :bar}]
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20 activesupport/test/core_ext/array_ext_test.rb
@@ -398,6 +398,18 @@ def initialize(target) @target = target end
def method_missing(*a) @target.send(*a) end
end
+ class DoubtfulToAry
+ def to_ary
+ :not_an_array
+ end
+ end
+
+ class NilToAry
+ def to_ary
+ nil
+ end
+ end
+
def test_array
ary = %w(foo bar)
assert_same ary, Array.wrap(ary)
@@ -438,4 +450,12 @@ def test_struct
o = Struct.new(:foo).new(123)
assert_equal [o], Array.wrap(o)
end
+
+ def test_wrap_returns_nil_if_to_ary_returns_nil
+ assert_nil Array.wrap(NilToAry.new)
+ end
+
+ def test_wrap_does_not_complain_if_to_ary_does_not_return_an_array
+ assert_equal DoubtfulToAry.new.to_ary, Array.wrap(DoubtfulToAry.new)
+ end
end
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9 railties/guides/source/active_support_core_extensions.textile
@@ -2229,7 +2229,14 @@ NOTE: Defined in +active_support/core_ext/array/conversions.rb+.
h4. Wrapping
-The class method +Array.wrap+ behaves like the function +Array()+ except that it does not try to call +to_a+ on its argument. That changes the behavior for enumerables:
+The class method +Array.wrap+ behaves like the function +Array()+ except:
+
+* If the argument responds to +to_ary+ the method is invoked. <tt>Kernel#Array</tt> moves on to try +to_a+ if the returned value is +nil+, but <tt>Arraw.wrap</tt> returns such a +nil+ right away.
+* If the returned value from +to_ary+ is neither +nil+ nor an +Array+ object, <tt>Kernel#Array</tt> raises an exception, while <tt>Array.wrap</tt> does not, it just returns the value.
+* It does not call +to_a+ on the argument, though special-cases +nil+ to return an empty array.
+
+
+ that it does not try to call +to_a+ on its argument. That changes the behavior for enumerables:
<ruby>
Array.wrap(:foo => :bar) # => [{:foo => :bar}]

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