Editing WoW:USERAPI setArgs

{{userfunc}} <!-- Leave this line in! -->

The setArgs() and getArgs() remember and retreive arguments for callback functions in a more memory efficient way.


 setArgs(myTable, "name", arg1, arg2, arg3,...)


 arg1,arg2,arg3,... = getArgs(myTable, "name"[, extra, arguments, ...])

== setArgs Parameters ==

=== Arguments ===
:(myTable, "name", list,of,arguments,...)

:;myTable : Table - where to store the arguments
:;"name" : String - prefix to give the arguments, if you are storing arguments for multiple callbacks, otherwise ""
:;... : List of arguments to be stored

=== Returns ===
:''nothing''

== getArgs Parameters ==

=== Arguments ===
:(myTable, "name"[, ...])

:;myTable : Table - where to retreive the arguments from
:;"name" : String - prefix used in setArgs
:;... : (optional) - extra arguments to use after the stored ones

=== Returns ===
:All arguments stored by setArgs(), optionally followed by the extra arguments supplied to getArgs()


== Example 1 ==
Just demonstrating how setArgs and getArgs actually work

 function out(...)
   for i=1,select("#", ...) do
     print(i.."="..tostring(select(i,...)))
   end
 end
 
 tbl = {}
 
 setArgs(tbl, "myArgList",  "a", nil, "3")
 out( getArgs(tbl, "myArgList",  "extra", nil, "cheese") )

====Result====
 1=a
 2=nil
 3=3
 4=extra
 5=nil
 6=cheese

== Example 2 ==
Demonstrating how callbacks could be implemented in a "library" / addon that wants to be able to accept callback registrations from other sources

=== "Library" ===

 local mytable = {}
 local function myUpdateHandler(this, delay)
   if mytable.callback then
   	mytable.callback( getArgs(mytable, "arg", delay) )
   end
 end
 
 function RegisterOnUpdateCallback(func, ...)
   mytable.callback = func
   setArgs(mytable, "arg", ...)
 end

(There obviously needs to be a [[frame]] created that calls myUpdateHandler via [[OnUpdate]] also, but that's out of scope for the example)

=== "User" ===

 function MyMod:OnUpdate(delay)
   print("OnUpdate fired after " delay " seconds");
 end
 
 function MyMod:Initialize()
   SetOnUpdateCallback(MyMod.OnUpdate, self)
 end

== Code ==

 local getArgs
 do
   local numargs
   local function _get(t, str, i, ...)
   	if i&lt;=numargs then
   		return t[format("%s%d", str, i)],  _get(t, str, i+1, ...)
   	end
   	return ...
   end
   		
   function getArgs(t, str, ...)
   	numargs = t[str.."#" or 0]
   	return _get(t,str,1, ...)
   end
 end
 
 local function setArgs(t, str, ...)
   local n = select("#", ...)
   for i=1,n do
     t[format("%s%d",str,i)]=select(i,...)
   end
   for i=n+1, (t[str.."#"] or 0) do
   	t[format("%s%d",str,i)]=nil
   end
   t[str.."#"] = n
 end