Re: Detailed On-line Explanation of What's New in 5.1?
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- Subject: Re: Detailed On-line Explanation of What's New in 5.1?
- From: "Alex Davies" <alex.mania@...>
- Date: 2008年6月30日 15:18:29 +0800
Veli-Pekka Tätilä wrote:
In particular, the new var-arg syntax baffles me even having read the
vararg second class citizen article in the Lua wiki. Why the change to
make vararg processing more cumbersome?
It's faster. A lot of vararg functions can be written now without any
creating any objects, where as before trying to write, for example, assert
in Lua would have been very slow. Now it just looks like this:
function assert(val, ...)
if not val then
error(... or "assertion failed")
end
return val, ...
end
Quite a bit nicer, neater and a lot faster then the old way where the last
line would look like:
return cond, unpack(arg)
And where you need to iterate over the arguments, or address them via
number, the creation of a table is incredibly simple:
local arg = {...}
I do liek the fact that the list has a name like ... now, and you can even
pass such lists to modules. Which reminds me, can I pass extra args to
modules when requiring them, like i can in Perl's use operator? How does
the module magiclly get its name as the first element of ... anyway?
According to http://www.lua.org/manual/5.1/manual.html#pdf-require require
passes modname to the loader, and does not take any additional arguments.
Surprised actually, thought it would pass them on.
- Alex