Re: RFE: table ctor syntax enhancement for many-to-one mappings
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- Subject: Re: RFE: table ctor syntax enhancement for many-to-one mappings
- From: Dirk Laurie <dpl@...>
- Date: 2011年8月19日 09:36:20 +0200
On Thu, Aug 18, 2011 at 10:46:27PM +0200, Lorenzo Donati wrote:
>
> I stumbled into this idea while writing a long set-like table. Wouldn't
> it be nice if the follwing:
>
>
> set = { a = true, b = true, [1] = true }
>
> could be abbreviated as:
>
> set = { ["a","b",1] = true }
>
Uh-oh. Bad timing. We've just been directed on another thread
to <http://en.wikipedia.org/wiki/Parkinson%27s_Law_of_Triviality>,
which refers to Wadler's Law:
the bulk of discussion on programming language design centers
around syntax (which, for purposes of the argument is considered
a solved problem), as opposed to semantics.
But to return to your point: surely this is a Lua idiom?
set = {}
for _,v in ipairs{"a","b",1} do set[v]=true end
The part that grows when the set is large, i.e. {"a","b",1},
is exactly the same size as in the proposal. The one-off part
is bigger, but the same code can also be used to add more elements
to the set later.
Dirk