diff options
Diffstat (limited to 'activesupport/lib/active_support/core_ext/array/wrap.rb')
-rw-r--r-- | activesupport/lib/active_support/core_ext/array/wrap.rb | 34 |
1 files changed, 30 insertions, 4 deletions
diff --git a/activesupport/lib/active_support/core_ext/array/wrap.rb b/activesupport/lib/active_support/core_ext/array/wrap.rb index e211bdeeca..06b2acd662 100644 --- a/activesupport/lib/active_support/core_ext/array/wrap.rb +++ b/activesupport/lib/active_support/core_ext/array/wrap.rb @@ -1,15 +1,41 @@ 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. + # Wraps its argument in an array unless it is already an array (or array-like). # - # It differs with Array() in that it does not call +to_a+ on - # the argument: + # Specifically: + # + # * If the argument is +nil+ an empty list is returned. + # * Otherwise, if the argument responds to +to_ary+ it is invoked, and its result returned. + # * Otherwise, returns an array with the argument as its single element. + # + # Array.wrap(nil) # => [] + # Array.wrap([1, 2, 3]) # => [1, 2, 3] + # Array.wrap(0) # => [0] + # + # This method is similar in purpose to <tt>Kernel#Array</tt>, but there are some differences: + # + # * 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}] # # Array("foo\nbar") # => ["foo\n", "bar"], in Ruby 1.8 # Array.wrap("foo\nbar") # => ["foo\nbar"] + # + # There's also a related idiom that uses the splat operator: + # + # [*object] + # + # which returns <tt>[nil]</tt> for +nil+, and calls to <tt>Array(object)</tt> otherwise. + # + # Thus, in this case the behavior is different for +nil+, and the differences with + # <tt>Kernel#Array</tt> explained above apply to the rest of +object+s. def self.wrap(object) if object.nil? [] |