Re: table construction: key is string with dash

[Rena <hyperhacker@...>]

On Wed, Sep 3, 2014 at 4:07 AM, Christopher Kappe <nox_diesque@web.de> wrote:
> Hello all,
>
> I don't know if this has been discussed before or if the question is too
> silly but I couldn't find anything on the topic by searching google and the
> mailing list archive.
>
> Concerning the construction of tables, I was under the assumption that
> { foo = bar } -- where foo is a string and bar is some variable
> is the same as
> { ["foo"] = bar }
> But - and that's the point of my email -
> { foo-fighter = bar }
> gives an error ('}' expected near '=').
>
> Probably the interpreter thinks that dash here is a minus operator and so
> foo and fighter must be number variables with a likewise numerical result of
> the subtraction and thus the "key-is-a-string" syntactic sugar doesn't
> apply. But this wouldn't happen, if the "=" sign was processed first (?).
>
> -- No necessary information below this line ;-)
> I bring this up because I really much would like to use such syntax. The
> background is that I like to create svg images with Lua scripts. This is
> easier, quicker and yields better results for me than struggling with
> programs like Inkscape, Draw or Dia. Especially the set of attributes for a
> svg tag is perfectly reflected by Lua tables. E.g. I can make a function
> call as
> svg.rectangle{ width=100, height=42, fill="black" }
> But attributes with a dash require the ugly syntax
> svg.rectangle{ fill="black", ["stroke-width"]=1.337 }
>
> So I wonder what you think. Could this kind of syntax be allowed in any
> later version of the language?
>
> Best regards,
> Nox
>

My solution has usually been to write it as stroke_width and then
gsub('_', '-') before writing. I can see some benefit to being able to
use various punctuation characters as key names (since I think they
wouldn't be valid in that position otherwise anyway), but it might
also get confusing.

-- 
Sent from my Game Boy.