What's wrong with my array initialization in ruby?

Question

Why is this a syntax error in ruby?

#!/usr/bin/ruby

servers = [ 
            "xyz1-3-l" 
    ,       "xyz1-2-l" 
    ,       "dws-zxy-l" 
    ,       "abcl" 
]

hostname_input = ARGV[0]
hostname = hostname_input.gsub( /.example.com/, "" )
servers.each do |server|
    if  hostname == server then 
            puts "that's the one"
            break
    end
end

... when I execute this script I get this output ...

$ ./test.rb abc1
./test.rb:5: syntax error, unexpected ',', expecting ']'
        ,       "xyz1-2-l" 
         ^
./test.rb:6: syntax error, unexpected ',', expecting $end
        ,       "dws-zxy-l" 
         ^

... if I simply put everything on the same line its ok ...

$ cat test.rb 
#!/usr/bin/ruby

servers = [ "xyz1-3-l" ,        "xyz1-2-l" ,    "dws-zxy-l" ,   "abcl" ]

hostname_input = ARGV[0]
hostname = hostname_input.gsub( /.example.com/, "" )
servers.each do |server|
        if  hostname == server then 
                puts "that's the one"
                break
        end
end
$ ./test.rb dws-zxy-l
that's the one

You don't need this sort of contortion in Ruby, trailing commas are ignored. — mu is too short
– mu is too short, Commented Apr 9, 2013 at 23:24
@muistooshort: Wait, what? I was about to be shocked to discover that I hadn't noticed in seven years of writing Ruby that trailing commas are ignored in arrays, so I tried writing one without them, and…syntax error. Did you mean something else? — Chuck
– Chuck, Commented Apr 9, 2013 at 23:27
@Chuck: Works for me with a = [1,2,3,] and even with newlines mixed in. Or did you do [1,2,3,,]? — mu is too short
– mu is too short, Commented Apr 9, 2013 at 23:33

Mark Thomas · Accepted Answer · 2013-04-10 02:00:50Z

3

Look ma, no commas (or quotes):

servers = %W[
    xyz1-3-l
    xyz1-2-l
    dws-zxy-l
    abcl
]

# => ["xyz1-3-l", "xyz1-2-l", "dws-zxy-l", "abcl"]

answered Apr 10, 2013 at 2:00

Mark Thomas

37.6k11 gold badges78 silver badges101 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Chuck · Accepted Answer · 2013-04-09 23:24:13Z

2

Newlines are significant in Ruby. You need to put the comma at the end of the line or use a backslash before your newline to indicate that the line is continuing (of course, in that case, what's the point in moving the comma to the next line?).

answered Apr 9, 2013 at 23:24

Chuck

238k31 gold badges306 silver badges392 bronze badges

1 Comment

Joshua Cheek Over a year ago

leading commas mean you can comment out a line without them being off by one. In the OP's case, training commas will work fine, too, but for things like options hashes, leading comma is nice because then you can delete or comment out the line, without having to edit the lines around it.

Collectives™ on Stack Overflow

What's wrong with my array initialization in ruby?

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related