Re: [PROPOSAL & PATCH] patches to support multi embedded values for userdata.

[Xavier Wang <weasley.wx@...>]

2011/9/3 Xavier Wang <weasley.wx@gmail.com>:
> Hi all in list, hi Roberto :)
>
> I have written a patch for Lua 5.2-beta, for support multi embedded
> values for lua's userdata. this used to deprecate the env table of
> userdata. this patch allow you embed more than one value to a
> userdata. it's very useful to implement light-weight array, or
> linked-list or show the dependency of objects.
>
> Reason:
>
> In Lua 5.1, we have env-table for function and thread and userdata.
> for function and thread, it holds all its 'global' variables. but for
> userdata, it's just a 'uservalue', used for contain user defined
> values. but In Lua5.2, we used _ENV to replace env table, but the
> userdata env is remained because it's useful. but the functional of
> userdata's env is to weak: it can only contain Table, if you want to
> link more than one value with your userdata, you have to put them into
> the env *table*, but a table is to heavy (56 bytes, vs TValue has only
> 8 bytes when enable the NaN trick), it's not suit for the embedded
> devices, etc.
>
> So I added four new api into Lua5.2-beta, they are:
>
> void *lua_newuserdataev(lua_State *L, size_t size, size_t extravalues);
> void lua_getuservalueev(lua_State *L, int idx, int vidx);
> void lua_setuservalueev(lua_State *L, int idx, int vidx);
> int lua_getuvcount(lua_State *L, int idx);
>
> you can use these new api to create a userdata with extra values (ev
> == extra values), you can access these values, or query the count of
> extra values. vidx accepted 1-based index to extra-values, and if vidx
> is negative,  is means the last 1-based value to the first one. 0 is
> always a invalid index (just the same rules of lua stack).
>
> the attachment is the patches to lua-5.2-beta, and a test module named
> array, and a working binary for Windows.
>
> Roberto, this function is very easy to implment, and is useful for
> binding C/C++ libraries to lua, useful to use lua to manage the
> dependency of userdatas, support a custom version of garbage collect,
> and back-compatible with the Lua 5.2-beta, Can you merge it into the
> Lua 5.2 trunk? or Is it has other issue? Hopes for your reply :)
>
> thank everybody in list, too :)
>

Attach a zip without binary :(

Attachment: Lua-5.2.0-beta_with_ev.zip
Description: Zip archive