Re: Popularity contest
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- Subject: Re: Popularity contest
- From: Dirk Laurie <dpl@...>
- Date: 2011年9月26日 10:52:14 +0200
On Mon, Sep 26, 2011 at 09:06:05AM +0200, steve donovan wrote:
> a useful bit of sugar would be:
>
> import print,table,io
>
> which makes suitable locals available. Can also say 'import sin, cos
> from math' of course.
I find in a file called `dplutils.lua`, this:
~~~~
function util.import(from,items,to)
-- import(from,nil,to) copies everything; can be used as shallow table copy
-- import(from,items,_ENV) copies items to current environment
-- import(from,items) copies items to global environment
-- import(from) copies everything to global environment
-- import(from,foo) replaces foo by a new table if foo is not a table
-- import("name") copies from require "name"
-- if `items` has only one item, it need not be put into a table
-- all versions return the table `to`
to = to or _G or getfenv() -- specified or Lua 5.2 or Lua 5.1
-- FAQ: Why make _G the default, not _ENV?
-- Ans: Otherwise in interactive mode nothing happens past the current line.
if type(from)=='string' then from=require(from) end
if type(to)~='table' then to={} end
if type(items)=='string' then items={items} end
if items
then for i=1,#items do to[items[i]] = from[items[i]] end
else for k,v in pairs(from) do to[k]=v end
end
return to
end
~~~~
I'm sure most of you have something of the kind, probably a little
more sophisticated.
Sure, I start every program with
util = import "dplutils"
util.import(util)
but is the proposed 'import sin,cos from math' really so much more
convenient than 'import(math,{"sin","cos"})' as to justify two new
keywords? (As I have confessed before, I'm a Python _apostate_).
Dirk