Re: [Kepler-Project] SAPI semantics in CGILua

["Dirk Feytons" <dirk.feytons@...>]

On 7/16/07, Hisham Muhammad <hisham.hm@gmail.com> wrote:
> In my code I often put type() check assertions, but for public APIs I
> believe the best practice would be to use check functions are
> preferred over lua_type() checks, because non-string objects can be
> used as strings (by having a __tostring function in their metatable)
> -- no reason to restrict string parameters to "real strings" only.

I wasn't aware that luaL_checkstring() invokes the __tostring
metamethod? Or in other words: do lua_isstring() and lua_tolstring()
check for and invoke __tostring metamethods?

> Perhaps the API spec could be improved to specify that whenever string
> or number arguments are mentioned, the check functions should be used
> and not lua_type enforcements.

I would like to see something like that in the docs yes: a note that
explains that when 'string' is mentioned it means 'any variable that
can be trivially coerced to a string i.e. for which lua_isstring()
returns true'. It might also be useful to advise the use of
luaL_checkstring()/luaL_checklstring() and the fact that it raises an
error when the conversion fails (not immediately clear from the
reference manual and indirectly mentioned in PiL2).

--
Dirk