Re: blocks in Lua (was Re: [PROPOSAL] [PATCH] simple method call)
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- Subject: Re: blocks in Lua (was Re: [PROPOSAL] [PATCH] simple method call)
- From: Tom N Harris <whoopdedo@...>
- Date: 2015年6月13日 21:05:51 -0400
On Saturday, June 13, 2015 07:53:59 AM Jay Carlson wrote:
> This is the spot where I suggest Lua get blocks:
>
> commands:foreach() in cmd do
> print(cmd)
> end
>
> Where "foreach" looks like:
>
> function foreach(l)
> for _,v in ipairs(l) do
> goto in(v)
> end
> end
>
> Where "goto in()" is like a function call to the block parameter.
>
> The block has no name. "goto in()" is special syntax like "…". There is no
> way for the callee to capture the block, and it is safe to allocate on the
> stack.
There's a whole lot of magic in what you describe, like the mysteriously
scoped "in" function that isn't a function.
What you're doing is essentially
function foreach(l,f) for _,v in ipairs(l) do f(v) end end
commands:foreach(print)
-- or rather
commands:foreach(function(v)
dosomething(v)
end)
So following the shorthand "" and {} call with string/table syntax, how about
a shorthand call with function syntax
args ::= '(' [explist] ')'
| tableconstructor
| LiteralString
| functiondef
functioncall ::= prefixexp args
and thus
commands:foreach function(v)
dosomething(v)
end
Then again, PUC-Rio is just as likely to remove shorthand functioncall syntax
as add any new ones. It's just a minor matter of convenience that doesn't
change the expressibility of the language significantly.
--
tom <telliamed@whoopdedo.org>