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class Array # 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. # # @example nil: an empty list # Array.wrap(nil) # => [] # @example an array: itself # Array.wrap([1, 2, 3]) # => [1, 2, 3] # @example an atom: array of length 1 # Array.wrap(0) # => [0] # # This method is similar in purpose to `Kernel#Array`, but there are some differences: # # * If the argument responds to +to_ary+ the method is invoked. `Kernel#Array` # moves on to try +to_a+ if the returned value is +nil+, but `Array.wrap` returns # such a +nil+ right away. # * If the returned value from +to_ary+ is neither +nil+ nor an +Array+ object, `Kernel#Array` # raises an exception, while `Array.wrap` 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: # # @example It does not molest hashes # Array(:foo => :bar) # => [[:foo, :bar]] # Array.wrap(:foo => :bar) # => [{:foo => :bar}] # # @example It does not do insane things to strings # 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 `[nil]` for +nil+, and calls to `Array(object)` otherwise. # # Thus, in this case the behavior is different for +nil+, and the differences with # `Kernel#Array` explained above apply to the rest of +object+s. def self.wrap(object) if object.nil? [] elsif object.respond_to?(:to_ary) object.to_ary || [object] else [object] end end end
Version data entries
7 entries across 7 versions & 1 rubygems