New Ruby syntax doesn't work everytime

Question

I would like to ask Ruby experts for explaination.

I can't use something like "foo-bar": true, but foobar: true works. Did anyone notice this?

This works:

In new Ruby syntax we can replace this hash rocket:

<%= f.submit "Save", :class => "btn" %>
                     ^-------------^

with this

<%= f.submit "Save", class: "btn" %>
                     ^----------^

This doesn't:

Now, how about symbols with two words? This doesn't work - syntax error!

<%= f.submit "Save", "data-disable-with": "Saving..." %>
                     ^------------------------------^

possible duplicate of [Is there any difference between the \`:key => "value"\` and \`key: "value"\` hash notations?](http://stackoverflow.com/questions/8675206/is-there-any-difference-between-the-key-value-and-key-value-hash-no) — mu is too short, Nov 06 '13 at 20:29

score 4 · Answer 1 · answered Nov 06 '13 at 21:03

The JSON style Hash syntax is for Hashes whose keys are Symbols which are valid Ruby identifiers. Your key is neither a Symbol (it's a String) nor a valid Ruby identifier (Ruby identifiers cannot contain a hyphen, because that creates an ambiguity with the binary infix - operator: does a-b mean the identifier a-b or does it mean "subtract b from a, i.e. a.-(b)?)

Timbinous · Answer 2 · 2013-11-06T21:18:28.977

-1

You are trying to set the key as a string instead of a symbol.

edited Nov 06 '13 at 21:18

answered Nov 06 '13 at 20:52

Timbinous

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I didn't see the minus symbols at first, sorry – Timbinous Nov 06 '13 at 21:18

New Ruby syntax doesn't work everytime

This works:

This doesn't:

2 Answers2