How do I unsplat something?

Ruby
1

Hi,
Is there any easy to unsplat an item?
ie. 1 becomes [1]
[2,3] remains [2,3] ?

so far i found:
a = *[1]
*b = *a #=> [1]
a = *[1,2]
*b = *a #=> [1,2]

but this doesn’t work if a is a hash, because hash overrides the to_a
method
a = *[{“a”=>1}]
*b = *a #=> [[“a”,1]] when i actually want: [{“a”=>1}]

Thanks for helping
-Patrick

2

On 12.08.2008 18:21, Patrick Li wrote:

but this doesn’t work if a is a hash, because hash overrides the to_a
method
a = *[{“a”=>1}]
*b = *a #=> [[“a”,1]] when i actually want: [{“a”=>1}]

What result are you trying to get?

robert

3

this do?

def unsplat(x)
return [x].flatten
end

4

Yup that does nicely. Thanks very much.

5

Hi,

On Tue, Aug 12, 2008 at 9:49 AM, Patrick Li [email protected]
wrote:

Yup that does nicely. Thanks very much.

Are you sure you want to flatten that far? Why not just arrayify?

Array(1) # => 1
Array([2,3]) # => [2,3]
Array([4,[5,6]]) # => [4,[5,6]]

~ j.

6

On Tue, Aug 12, 2008 at 12:39 PM, Shadowfirebird
[email protected] wrote:

this do?

def unsplat(x)
return [x].flatten
end

Just a warning, #flatten is not the inverse of splat, because it
recurses arbitrary levels of nested array.

–
Avdi

Home: http://avdi.org
Developer Blog: Avdi Grimm, Code Cleric
Twitter: http://twitter.com/avdi
Journal: http://avdi.livejournal.com

7

I can’t use Array() because I want:
{“a”=>2} to become [{“a”=>2}]

so far: flatten is the best so far… except that it recursively
flattens inner arrays too… which is not ideal but workable for my
current use.

8

On Aug 12, 1:14 pm, Patrick Li [email protected] wrote:

I can’t use Array() because I want:
{“a”=>2} to become [{“a”=>2}]

so far: flatten is the best so far… except that it recursively
flattens inner arrays too… which is not ideal but workable for my
current use.

–
Posted viahttp://www.ruby-forum.com/.

There was a ruby quiz that included implementations of a single-level
flatten[1]. Taking from James G.'s solution[2], and minding your
requirements regarding hashes, what about this:

def unsplat(the_splatted)
if the_splatted.kind_of?(Hash)
[the_splatted]
else
[the_splatted].inject(Array.new) { |arr, a| arr.push(*a) }
end
end

unsplat(1) # => [1]
unsplat([2,3]) # => [2, 3]
unsplat([4,[5,6]]) # => [4, [5, 6]]
unsplat({‘a’=>2}) # => [{“a”=>2}]

HTH,
Chris

[1] Ruby Quiz - One-Liners (#113)
[2] http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/238693

9

lol yeah. Shadowfirebird’s hack is the one i’m currently using. I just
wanted to know if there was a easier one-liner way of doing it. It
seemed plausible for there to be reverse operator given a splat
operator.

Anyway thanks for the help
-Patrick

10

How about:

def unsplat(thing)
if thing.kind_of?(Array)
thing
else
[thing]
end
end