Re: Lua 5.3 Suggestion: extend lua_(get|set)uservalue() to associate userdata-to-userdata

[Philipp Janda <siffiejoe@...>]

Am 02.12.2013 07:01 schröbte Sean Conner:
> It was thus said that the Great Sir Pogsalot once stated:
> > I am saying that it is out of my control, as it is done by code I did not
> > write.  So the metatable check works but the subsequent rawlen() fails.
>
>    That's what I'm not understanding---the call to lua_rawlen().  To me, it
> sounds like a defensive programmer going overboard.  Personally, I don't
> believe in defensive programming as it hides bugs [1].  Trust the
> programmer; do NOT trust the outside world though.

... and don't trust that two programmers that have never even talked to 
each other will always produce compatible code.

Consider two C extension modules written by different authors, which use 
the same name for `luaL_newmetatable` but for different C types. No 
trust in either programmer will prevent a crash when a user loads both 
modules.

Maybe `luaL_newmetatable` should raise an error instead of returning `0` 
if there already is a metatable for a given name in the registry.

>    -spc (Fail fast)

Philipp (still satisfied with `luaL_checkudata` alone)