FFI serializer fake metamethod

output.txt

$ luajit ~/Desktop/serialize_metamethod.lua 
2 =%= 3
cdata<struct 98>: 0x0004d738

serializer_fake_metamethod.lua

local ffi = require 'ffi'

local Foo_t = ffi.metatype( ffi.typeof('struct { int a, b; }'), {
    __index = {
        -- return "a =%= b"
        _serialize = function( self )
            return self.a .. ' =%= ' .. self.b
        end,
    }
})

local Bar_t = ffi.typeof('struct { int c, d; }')


-- just do tostring and write to file
local function default_serializer( obj )
    return tostring(obj)
end


local function serialize( obj )
    local success, serializer = pcall(function() return obj._serialize end)
    if success then
        return serializer( obj )
    elseif default_serializer then
        return default_serializer( obj )
    else
        return 'no serializer'
    end
end

-- added loop to get trace compiler output
for i = 0, 1000 do
    for _, v in ipairs{ Foo_t(2,3), Bar_t(2,3) } do
        io.stdout:write( 'ser:', serialize(v), '\n' )
    end
end