sunday afternoon whishlist: append/stream operator
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- Subject: sunday afternoon whishlist: append/stream operator
- From: Oliver Schmidt <oschmidt_do_not_send_email_to_this_address@...>
- Date: 2010年6月01日 21:27:55 +0200
Hi,
On 09/05/10 17:36, Klaus Ripke wrote:
Could x[] be syntactic sugar for x[#x+1] ?
It would make appending to lists so much nicer.
I also think that a nice syntactic form for appending to lists would
increase Lua's usability as configuration language.
Consider the use case, that the user has to configure some lists of
names (e.g. filenames) for some kind of processing. Some names may
belong to different lists. So it would be nice, if the user may define
his own lists and build configuration lists together from his user
defined lists. So the user can group his names and mention each name
only once.
IMHO a nice way for this could be a stream operator "<<" (this could
also be useful for other use cases).
E.g.
t1 = { "a", "b", "c"}
t2 = { "x", "y" }
t1 << { "d", "e" } << "f" << t2 << "z"
Would result in t1 pointing to the table { "a", "b", "c", "d", "e", "f",
"x", "y", "z" }
The stream operator should be overwritable in the metatable, with
default implementation:
function __stream(a, b)
if type(a) ~= "table" then error("...") end
if type(b) == "table" then
for i = 1, #b do
a[#a + 1] = b[i]
end
else
a[#a + 1] = b
end
return a
end
What do you think?
Best regards,
Oliver