新的Ruby语法并非每次都有效

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..." %>
                     ^------------------------------^

Answer 1

The JSON style Hash syntax is for Hash es whose keys are Symbol s 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 ab mean the identifier ab or does it mean "subtract b from a , ie a.-(b) ?)

Answer 2

您试图将密钥设置为字符串而不是符号。