Re: accessing embedded structs
- From: Mike Pall <mike-1205@xxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Mon, 28 May 2012 23:45:12 +0200
William Adams wrote:
> And would call it like this:
>
> struct bar abar;
>
> func(&abar.starting)
>
> Is this how I would do this in LuaJIT? (assuming 'func()' is still on the 'C'
> side)
>
> local abar = ffi.new("struct bar");
>
> local ending_offset = ffi.offsetof("struct bar", "ending")
>
> local ptr = ffi.cast("struct bar *", abar)
>
> ptr = ptr + ending_offset
>
> func(ptr)
Nope, just call:
func(abar.starting)
-or-
func(abar.ending)
Accessing a nested struct creates a reference to the inner struct
(and not a copy of it). This can be treated just like the inner
struct or a pointer to the inner struct (e.g. when passed to a C
function).
And yes, if func() modifies fields of its argument, this _does_
modify parts of 'abar'.
--Mike
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