Re: ["all"] as an Lvalue?

[Hisham <h@...>]

On 28 March 2016 at 22:04, Daurnimator <quae@daurnimator.com> wrote:
> On 29 March 2016 at 11:55, Steve Litt <slitt@troubleshooters.com> wrote:
>> Hi all,
>>
>> I'm writing a document on Luakit, and in my section on making fonts
>> bigger, I need to give instructions to edit the domain_props table,
>> which looks something like this:
>>
>> =====================================================
>> domain_props = {
>>     ["all"] = {
>>         enable_scripts          = false,
>>         enable_plugins          = false,
>>         enable_private_browsing = false,
>>         user_stylesheet_uri     = "",
>>     },
>>     ["youtube.com"] = {
>>         enable_scripts = true,
>>         enable_plugins = true,
>>     },
>> }
>> =====================================================
>>
>> It looks like domain_props is a table whose two elements are each
>> tables, named ["all"] and ["youtube.com"] respectively. I've never seen
>> something like ["all"] being the name of a table element or a variable
>> name before. What's going on, is ["all"] an anonymous table containing
>> element "all"? I just don't understand this syntax, and why somebody
>> would do this. What am I missing?
>
> { foo = "bar" }
> is actually just short for:
> { ["foo"] = "bar" }
>
> The first shorter form however only works for keys that are valid identifiers.
> Which means you have to use the 2nd form for:
>   - keywords (e.g. {["end"] = 1234})
>   - non-valid identifiers
>       - e.g. starting with a number: {["1thing"] = item}
>       - e.g. containing a ".": {["youtube.com"] = "a website"}
>   - non-string keys. e.g. {[50] = "number as key"}

All three answers are correct, but if this was Stack Overflow yours
would be the one I would upvote, for being the clearest. :)

-- Hisham