Re: Possible to store a reference to a lua table in an ffi struct?
- From: Evan Wies <evan@xxxxxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Sun, 23 Mar 2014 08:27:54 -0400
On 3/22/14, 8:22 PM, Kaj Eijlers wrote:
Using that same technique, you can store just the
vector<string>-replacement table in the metatable. The downside
of this approach is that you will need a different
metatype/metatable for each instance (unless the intention is to
share this vector<string> among among instances, i.e. a C++ static
class member).
For example:
t = ffi.metatype( "struct { int a, b, c; }", { __index = { vstr =
{} } })
foo = t()
foo.vstr[#foo.vstr+1] = "string1"
-Evan
Hmmmmm, No I need a vector per instance, so I think I'll go with a
member that is a ctype with a metatable for push_back() and the likes.
But thanks for the idea, I'll keep it in mind :o)
You can have a vector per instance. But it needs to be created with a
new metatype each time and ffi.metatype is not JIT compiled (but maybe
not such a big deal with 2.1 and trace stitching).
local struct_t = ffi.typeof("struct { int a, b, c; }") -- make one ctype
local function new_instance()
-- but have many metatatypes
return ffi.metatype( struct_t, { __index = {
vstr = setmetatable( {}, {
__index = { push_back = function(t, s) t[#t+1] = s end }
})
}})
end
f = new_instance()
f.vstr:push_back("f")
g = new_instance()
g.vstr:push_back("g")
-Evan
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