why Array.wrap ?

rubyonrails-core
1

Hey Active Support defines Array.wrap (copied below). What's the difference between that and the Ruby builtin Array() method:

    Array(nil) # =>     Array([0]) # => [0]

    class C       def to_ary         [0]       end     end     Array(C.new) # => [0]

    Array(0) # => [0]

Perhaps it was just an overlook that Array() exists?

-- fxn

class Array   # Wraps the object in an Array unless it's an Array. Converts the   # object to an Array using #to_ary if it implements that.   def self.wrap(object)     case object     when nil            when self       object     else       if object.respond_to?(:to_ary)         object.to_ary       else         [object]       end     end   end end

2

IIRC, it's different on 1.9.

3

There's also:

Array(:a=>:b)

=> [[:a, :b]]

Mighty annoying.

4

Ah I tried as well with same result:

[xnoria@ruby-versions ~]$ irb191 irb(main):001:0> Array(nil) => irb(main):002:0> Array(0) => [0] irb(main):003:0> Array([0]) => [0] ... irb(main):007:0> irb(main):008:0* class C irb(main):009:1> def to_ary irb(main):010:2> [0] irb(main):011:2> end irb(main):012:1> end => nil irb(main):013:0> Array(C.new) => [0]

5

IIRC, it's different on 1.9.

I don't think its a 1.9 thing. It had something to do with strings being treated as Enumerable. See this:

Array("helo \n world")

=> ["helo \n", " world"]

Array.wrap("helo \n world")

=> ["helo \n world"]

-Mark

6

Array("foo\nbar") # => ["foo\n", "bar"]

Array.wrap("foo\nbar") # => ["foo\nbar"]

jeremy

7

Array() does too much. We want a uniform wrapper with no surprises.

jeremy

8

Ah yes, Array() calls #to_a also.

9

Excellent I'll the hash example and those to the RDoc and AS guide.

10

Understood.

I wanted to know the difference because I am documenting it. According to the Pickaxe and Flanafan & Matz the difference is exactly that Array.wrap does not call to_a, and those examples depict this.

11

Ugh sorry, Flanagan.

12

That's true, for example the return value of Array("foo\nbar") depends on the Ruby version because strings are not enumerables in 1.9. So you get ["foo\nbar"] in 1.9, and ["foo\n", "bar"] in 1.8.

So Array.wrap is portable as long as +to_ary+ is portable.