diff options
-rw-r--r-- | activesupport/lib/active_support/core_ext/array/wrap.rb | 23 | ||||
-rw-r--r-- | railties/guides/source/active_support_core_extensions.textile | 29 |
2 files changed, 48 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 09a1c2e5a1..06b2acd662 100644 --- a/activesupport/lib/active_support/core_ext/array/wrap.rb +++ b/activesupport/lib/active_support/core_ext/array/wrap.rb @@ -1,5 +1,17 @@ class Array - # <tt>Array.wrap</tt> is like <tt>Kernel#Array</tt> except: + # Wraps its argument in an array unless it is already an array (or array-like). + # + # 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 @@ -15,6 +27,15 @@ class Array # # 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? [] diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile index fcf4ae29ba..136fcde82a 100644 --- a/railties/guides/source/active_support_core_extensions.textile +++ b/railties/guides/source/active_support_core_extensions.textile @@ -2214,14 +2214,27 @@ NOTE: Defined in +active_support/core_ext/array/conversions.rb+. h4. Wrapping -The class method +Array.wrap+ behaves like the function +Array()+ except: +The method +Array.wrap+ wraps its argument in an array unless it is already an array (or array-like). + +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. + +<ruby> +Array.wrap(nil) # => [] +Array.wrap([1, 2, 3]) # => [1, 2, 3] +Array.wrap(0) # => [0] +</ruby> + +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. - - that it does not try to call +to_a+ on its argument. That changes the behavior for enumerables: +The last point is particularly worth comparing for some enumerables: <ruby> Array.wrap(:foo => :bar) # => [{:foo => :bar}] @@ -2231,6 +2244,16 @@ Array.wrap("foo\nbar") # => ["foo\nbar"] Array("foo\nbar") # => ["foo\n", "bar"], in Ruby 1.8 </ruby> +There's also a related idiom that uses the splat operator: + +<ruby> +[*object] +</ruby> + +which returns +[nil]+ 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. + NOTE: Defined in +active_support/core_ext/array/wrap.rb+. h4. Grouping |