Class: Array

Inherits:
Object show all
Defined in:
lib/core_ext/array.rb,
lib/core_ext/blank.rb

Class Method Summary collapse

Class Method Details

.wrap(object) ⇒ Object

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 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:

Array(:foo => :bar)      # => [[:foo, :bar]]
Array.wrap(:foo => :bar) # => [{:foo => :bar}]

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 objects.



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# File 'lib/core_ext/array.rb', line 36

def self.wrap(object)
  if object.nil?
    []
  elsif object.respond_to?(:to_ary)
    object.to_ary || [object]
  else
    [object]
  end
end