Re: How to return table key/value pairs in a particular order?

[Sean Conner <sean@...>]

It was thus said that the Great Duncan Cross once stated:
> On Sat, Nov 28, 2015 at 11:14 PM, Paul Merrell <marbux@gmail.com> wrote:
> > I have a prototype table for substituting character strings with UTF8
> > characters:
> >
> >   local tSub = {
> > ["%-%-%-"] = "—",
> > ["%-%-"] = "–",
> > ["%.%.%."] = " … "}
> >
> > My problem is that the first key/value pair must be processed before
> > the second key/value pair because of overlapping characters in the
> > keys, but the order in which Lua returns table key/value pairs is
> > unpredictable, leading to buggy results in the substitutions.
> >
> > Eventually the script would make many other substitutions, but I seem
> > to be stuck here at the prototype stage because of the unpredictable
> > return order.
> >
> > How might I work around this?
> 
> To address this specific case instead of the general question of
> ordered key/value pairs in Lua: Assuming the keys and values are being
> used as the "pattern" and "repl" parameters to a string.gsub() call, I
> would try replacing the first two entries with this one:
> 
>  ["%-%-%-?"] = {["---"]="—", ["--"]="–"},
> 
> Are there many other instances where order is important?

  It's only important when a shorter match would match a longer match, such
with the dashes above.  There are potentially other patterns too.  My
blogging software [1] uses the following abbreviations:

	---	&mdash;
	--	&ndash;
	...	&hellip;
	..	&#8229; -- I'm not sure if this has a name or not

  The only other type of thing might be TLAs [2] or ETLAs [3], like PCM
(Pulse coded modulation) and PCMCIA (People Can't Memorize Computer Industry
Acronyms).  If you wanted to extend those out [4], you would have to list
PCMCIA first, or you may get Pulse Coded Modulation Central Intelligence
Agency, which may not be what you wanted.

  -spc

[1]	https://github.com/spc476/mod_blog
	Written in C, uses Lua only for configuration.

[2]	Three Letter Acronym

[3]	Extended Three Letter Acronym

[4]	For example, like
	<acronym title="Cooking Institute of America">CIA</acronym>