wrap
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- What's this?
wrap(object)
public
Wraps its argument in an array unless it is already an array (or array-like).
Specifically:
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If the argument is nil an empty list is returned.
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Otherwise, if the argument responds to to_ary it is invoked, and its result returned.
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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:
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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.
raises an exception, while Array.wrap does not, it just returns the value.
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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 [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.