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Re: 'in' keyword today (was Re: mathlib)

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On Apr 9, 2014, at 1:54 PM, steve donovan <steve.j.donovan@gmail.com> wrote:
> https://gist.github.com/stevedonovan/10259826
> 
> require 'from'
> local sin,cos,tan = slots(3) from(math)
> local import,printf = slots(2) from 'pl.utils'
> local pretty,utils,xml = slots(3) from 'pl.*’
Let the hack fest continue! :D
Yet another hack for your entertainment:
local upper, lower = import from( 'string' )
print( 'upper', upper, upper( 'a' ) )
print( 'lower', lower, lower( 'B' ) )
> upper	function: 0x1034049b0	A
> lower	function: 0x1034045d0	b
With prefix, just because:
local mmin, mmax = import from( 'math', 'm’ )
print( 'mmin', mmin, mmin( 1, 2 ) )
print( 'mmax', mmax, mmax( 1, 2 ) )
> mmin	function: 0x103402740	1
> mmax	function: 0x1034026d0	2
Implementation details left to the imagination… but see bellow if you really must...
local import = nil
local function from( aName, aPrefix )
 local aModule = require( aName )
 local aPrefix = aPrefix or ''
 local anIndex = 2
 while true do
 anIndex = anIndex + 1
 if debug.getlocal( 2, anIndex ) == nil then
 break
 end
 end
 for anIndex = anIndex - 1, 1, -1 do
 local aName, aValue = debug.getlocal( 2, anIndex )
 local aKey = aName:sub( aPrefix:len() + 1 )
 if aModule[ aKey ] == nil or aValue ~= nil then
 break
 end
 debug.setlocal( 2, anIndex, aModule[ aKey ] )
 end
end
local upper, lower = import from( 'string' )
print( 'upper', upper, upper( 'a' ) )
print( 'lower', lower, lower( 'B' ) )
local mmin, mmax = import from( 'math', 'm' )
print( 'mmin', mmin, mmin( 1, 2 ) )
print( 'mmax', mmax, mmax( 1, 2 ) )

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