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On 26-Aug-05, at 9:35 AM, Chris Marrin wrote:

It would not be hard to add something to CallInfo to indicate that this method was called with the SELF instruction. That would no longer allow this:

    instance.g(instance, instance2)

in place of this:


but it would still be compatible because I'm making the ':' syntax a requirement in my object system. The rest of Lua works as it always has.

Anyway, does this seem like a reasonable approach?

The problem with this is that sometimes you need to call an instance method supplying the actual instance. This shows up at odd moments; the simplest example I can think of is the following:

table.foreach calls a function for every k,v in a table. It could be written:

function table.foreach(tab, func)
  for k, v in pairs(tab) do
    local rv = func(k, v)
    if rv then return rv end

Now, suppose I actually want to invoke an object method, instead of calling a function? I could do that with an explicit wrapper:

  table.foreach(tab, function(k, v) return obj:method(k, v) end)

but that would get tedious, so I would want to refactor it:

function table.foreachmeth(obj, tab, method)
  for k, v in pairs(tab) do
    local rv = obj[method](obj, k, v)
    if rv then return rv end

table.foreachmeth(obj, t, "send")

I could even introduce that into the object:

obj.foreach = foreachmeth
obj:foreach(tab, "send")

How would I write this if the method refused to execute unless self-called? The best I can come up with is filling the method name into a template and then compiling the template, which seems yukky.