Re: More on environments and objects
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- Subject: Re: More on environments and objects
- From: Rici Lake <lua@...>
- Date: 2005年8月26日 11:38:22 -0500
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:
instance:g(instance2)
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
end
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
end
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.