Class: Array
Class Method Summary collapse
-
.wrap(object) ⇒ Object
Wraps its argument in an array unless it is already an array (or array-like).
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 neithernil
nor anArray
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-casesnil
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 |