Re: local pre-declarations
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: local pre-declarations
- From: Asko Kauppi <asko.kauppi@...>
- Date: Wed, 1 Sep 2004 18:29:10 +0300
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 )