WoW:Using the argument '...' efficiently - Revision history

Move page script: Move page script moved page Using the argument '...' efficiently to WoW:Using the argument '...' efficiently without leaving a redirect

2023-08-15T04:49:15Z

Move page script moved page Using the argument '...' efficiently to Using the argument '...' efficiently without leaving a redirect

← Older revision	Revision as of 04:49, 15 August 2023
(No difference)

WoWWiki>Starlightblunder: merge candidate

2010-09-12T13:23:12Z

merge candidate

← Older revision		Revision as of 13:23, 12 September 2010
Line 1:		Line 1:
			{{merge\|Function arguments}}
	{{tocright}}		{{tocright}}
	With patch 2.0 and the upgrade to lua 5.1, the '...' arg is much more powerful and less memory intensive than it was previously. here's some handy tips on how to use this new functionality		With patch 2.0 and the upgrade to lua 5.1, the '...' arg is much more powerful and less memory intensive than it was previously. here's some handy tips on how to use this new functionality

WoWWiki>Mikk: Category:HOWTOs

2007-07-17T09:30:04Z

Category:HOWTOs

← Older revision		Revision as of 09:30, 17 July 2007
Line 47:		Line 47:
	end		end

	[[Category:~~Interface Customization~~]]		[[Category:HOWTOs\|U]]

WoWWiki>Adys at 14:17, 31 December 2006

2006-12-31T14:17:21Z

← Older revision		Revision as of 14:17, 31 December 2006
Line 46:		Line 46:
	end		end
	end		end

			[[Category:Interface Customization]]

WoWWiki>Tekkub: Bad cat, this is not a formula or game mechanics, it's UI/API stuff... but not really documentation...

2006-12-30T01:16:43Z

Bad cat, this is not a formula or game mechanics, it's UI/API stuff... but not really documentation...

← Older revision		Revision as of 01:16, 30 December 2006
Line 46:		Line 46:
	end		end
	end		end

	~~[[Category:Formulas and Game Mechanics]]~~

WoWWiki>Jeoh at 01:12, 30 December 2006

2006-12-30T01:12:11Z

← Older revision		Revision as of 01:12, 30 December 2006
Line 46:		Line 46:
	end		end
	end		end

			[[Category:Formulas and Game Mechanics]]

WoWWiki>Tekkub at 00:06, 30 December 2006

2006-12-30T00:06:12Z

New page

{{tocright}}
With patch 2.0 and the upgrade to lua 5.1, the '...' arg is much more powerful and less memory intensive than it was previously. here's some handy tips on how to use this new functionality

== Hooking ==
Previously, the ... arg would create a table 'args' if called. This allocated a table into memory, and thus became a source of garbage churn. A very common pitfall of this came from hooking:
local f = somefunc
somefunc = function(...)
-- do some crap
return f(unpack(args))
end
Now if this function is called often, or there are many hooks like this, there will be a significant hit on performance. With lua 5.1 we can do this hook with no memory wasted
local f = somefunc
somefunc = function(...)
-- do some crap
return f(...)
end

=== Post-hooks ===
The new functionality also allows for a nice clean post hook to be made. In this example we need the first arg passed to the function, and we wish to maintain a full proper hook. That means every arg is passed to the hooked function, and every return from that is returned back from our function.
local f = somefunc
local ph = function(a1, ...)
-- do something with a1
return ...
end
somefunc = function(a1, ...)
return ph(a1, f(a1, ...)
end

== Iterations ==
As with hooking, iteration over arbitrary number of args would create a table and thus waste memory. With lua 5.1 we can do this cleanly in a for loop
function f(...)
for i=1,select("#", ...) do
local x = select(i, ...)
-- do something with x
end
end

== Recursion ==
Clean recursive functions are simple with ...
function r(x, ...)
local y = x*x
if select("#", ...) > 0 then
return y, r(...)
else
return y
end
end