Shortcut for x = [x] unless x.is_a?(Array)

Rails
1

Sorry for double posting this on the Ruby section, I realized this is
kind of a rails question since it might relate to ActiveSupport.

Is there any prettier or cleaner way to write

x = [x] unless x.is_a?(Array)

I’ve looked into Array() and hash.to_a, but these will not give the
intended result as above.

Thanks in advance.

2

Aryk G. wrote:

Thanks in advance.

I’m curious if someone can do better, but here’s mine…

x = [x].flatten

disclaimer: won’t give desired results on multi-dimensional arrays.

–
http://www.5valleys.com/
http://www.workingwithrails.com/person/8078

3

You can use Array().

a = [1]
=> [1]

b = 2
=> 2

Array(a)
=> [1]

Array(b)
=> [2]

  • Gabe
4

Hey guys,

Thanks for the responses.

I don’t think any of those quite work. Here is a sample from irb:

hash = {:x => {:y => :z}}
=> {:x=>{:y=>:z}}

[hash]
=> [{:x=>{:y=>:z}}] # what im trying to get

[*hash]
=> [[:x, {:y=>:z}]]

hash.to_a
=> [[:x, {:y=>:z}]]

Array(hash)
=> [[:x, {:y=>:z}]]

Now, if I was going to do hash.each {|k,v|}, i dont think this would
matter, but we can’t assume thats always the case.

5

On Mar 10, 2008, at 3:15 PM, Aryk G. wrote:

Thanks in advance.

x = [*x]

Cheers-

6

What does het asterisk mean? Never seen that before…

7

Hi –

On Tue, 11 Mar 2008, LeonB wrote:

What does het asterisk mean? Never seen that before…

It “unwraps” an array into a list of values.

array = [1,2,3]
[array] # => [[1,2,3]]
[*array] # => [1,2,3]

It also flows the other way, especially in method parameter syntax:

def m(*args); end

m(1,2,3)

The list 1,2,3 will be wrapped in the array args. The fact that args
is an array also means that it doesn’t care whether or not it’s empty.
Thus it represents optional arguments (unlike a plain parameter, which
doesn’t already represent an object and therefore needs an argument
matched to it).

David

–
Upcoming Rails training from David A. Black and Ruby Power and Light:
ADVANCING WITH RAILS, April 14-17 2008, New York City
CORE RAILS, June 24-27 2008, London (Skills Matter)
See http://www.rubypal.com for details. Berlin dates coming soon!

8

Hi –

On Tue, 11 Mar 2008, Alain R. wrote:

x = [*x]
What does het asterisk mean? Never seen that before…

It’s the splat operator.

Or, as I prefer to call it, the unar[r]ay (unary unarray) operator :slight_smile:

David

–
Upcoming Rails training from David A. Black and Ruby Power and Light:
ADVANCING WITH RAILS, April 14-17 2008, New York City
CORE RAILS, June 24-27 2008, London (Skills Matter)
See http://www.rubypal.com for details. Berlin dates coming soon!

9

x = [*x]
What does het asterisk mean? Never seen that before…

It’s the splat operator.

See:

Alain

10

I thought it was only used in method arguments… Thanks!

From: [email protected]
[[email protected]] On Behalf Of David A. Black
[[email protected]]
Sent: 11 March 2008 15:44
To: [email protected]
Subject: [Rails] Re: shortcut for x = [x] unless x.is_a?(Array)

Hi –

On Tue, 11 Mar 2008, Alain R. wrote:

x = [*x]
What does het asterisk mean? Never seen that before…

It’s the splat operator.

Or, as I prefer to call it, the unar[r]ay (unary unarray) operator :slight_smile:

David

–
Upcoming Rails training from David A. Black and Ruby Power and Light:
ADVANCING WITH RAILS, April 14-17 2008, New York City
CORE RAILS, June 24-27 2008, London (Skills Matter)
See http://www.rubypal.com for details. Berlin dates coming soon!

11

Would it make sense to overwrite the #to_a function for Hash.

So instead of

h = { “c” => 300, “a” => 100, “d” => 400, “c” => 300 }
h.to_a » [[“a”, 100], [“c”, 300], [“d”, 400]]

It would be:

h = { “c” => 300, “a” => 100, “d” => 400, “c” => 300 }
h.to_a » [{ “c” => 300, “a” => 100, “d” => 400, “c” => 300 }]

What would this break? You can still do the hash.each{|k,v|} with this.
What am I missing?

12

None of these methods, including the unarray operator seem to be doing
the trick:

hash = {:x => {:y => :z}}
=> {:x=>{:y=>:z}}

[hash]
=> [{:x=>{:y=>:z}}] # what im trying to get

[*hash]
=> [[:x, {:y=>:z}]]

hash.to_a
=> [[:x, {:y=>:z}]]

Array(hash)
=> [[:x, {:y=>:z}]]

All the other methods break up the hash into key/value pairs, I still
want the hash intact.

So are there any shortcuts for " x = [x] unless x.is_a?(Array) " when x
is a Hash?