Good point. I have a case here (and from what I have read on the mailing list I am not alone), where I need to integrate FFI types into some other type checking system. A classical way of doing type checking in Lua is looking at the metatable attributed to one object (or checking some field (like __typename) in the metatable of this object). Right now, it is impossible. There are workarounds. Like using tonumber(ffi.typeof()), and keeping some additional table which tells if the object is part of the type system or not, but that is quite ugly, where a simple ffi.getmetatype() could do the job. From what I have read in previous post, you do not encourage playing with the type system. I totally understand that, but I am maintaining a large library, which includes many different modules, and which does not rely solely on FFI. I do have to merge two different worlds (classical Lua and FFI), unfortunately. More generally when one hides something in the metatable (a global property of the “class” of a given object), right now one cannot retrieve it easily. Once in while, the case occurs, someone complains to me, and one has to play with the tonumber(ffi.typeof())+additional table trick. Ronan. > On Nov 26, 2014, at 9:31 AM, Mike Pall <mike-1411@xxxxxxxxxx> wrote: > > Ronan Collobert wrote: >> At this time there is no (easy) way with luajit+ffi to get the metatable of >> a cdata/ctype. > > IMHO this is a classic instance of: http://xyproblem.info > Why would you want to get the metatable of a cdata object? > > --Mike >
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