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Ruby 1.9 hash with a dash in a key

Posted by: admin November 30, 2017 Leave a comment


In ruby 1.9 is there a way to define this hash with the new syntax?

irb> { a:  2 }
=> {:a=>2}

irb> { a-b:  2 }
SyntaxError: (irb):5: syntax error, unexpected tLABEL
{ a-b:  2 }

with the old one, it’s working:

irb> { :"a-b" =>  2 }
=> {:"a-b"=>2}

You also can use next syntax

{a: 1, b: 2, 'c-c': 3, d: 4}


There are some legitimate symbols that cannot be used with the new syntax. I cannot find a reference, but it appears that a symbol name matching /^[a-zA-Z_][a-zA-Z_0-9]*[!?]?$/ is allowed with the new syntax. The last character may be the special character “!” or “?”.

For any symbol that does not meet these restrictions, you have to use the Ruby 1.8 syntax, :'my-symbol-name'


To use dashes with the new syntax:

<%= link_to "Link", link_path, {data: {something: 'value1', somethingelse: 'value2'}} %>

This will generate:

<a href="/link" data-something='value1' data-somethingelse='value2'>Link</a>

This might not exactly be your particular use case, but I found this post while trying to find an answer myself so I thought I’d share my findings.


You can combine the old and new syntax:

{a: 1, b: 2, :'c-c' => 3, d: 4}