Re: local pre-declarations

[Asko Kauppi <asko.kauppi@...>]

For those interested, here's the outcome of my 'local predeclarations' 
cry.

This approach allows both the using and target functions to be declared 
in the regular way. None of the metamethods are really necessary, they 
serve merely as a safety net agains mistyped (nil) values and such.

The '__call' method allows for "UPCALL( 'Loc_ShellCommand', cmd )" 
syntax, but I'm not very fond of that..

-ak


  --
  local UPCALL= {}   -- set of functions where we need out-of-scope 
access

  setmetatable( UPCALL,
    {
    __newindex= function( tbl, key, val )
                    if not val then error "Predeclaring to 'nil'.. are 
you mad?" end
                    rawset( tbl, key, val )
                end,
    --
    __index=    function( tbl, key )    -- only called when value was 
'nil'
                    error( "Function not predefined: "..key )
                end,
    --
    __call=     function( tbl, name, ... )
                    local f= assert( tbl.name, "Function not 
predefined: "..name )
                    f( unpack(arg) )
                end
    } )

Usage:
	local function whatever()
		...
	  	UPCALL.Loc_ShellCommand( cmd )
		...
	end

Later:
  	local function Loc_ShellCommand( cmd )
		...
  	end
  	UPCALL.Loc_ShellCommand= assert( Loc_ShellCommand )