Re: Equality...
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: Equality...
- From: Luiz Henrique de Figueiredo <lhf@...>
- Date: Tue, 3 Aug 1999 17:44:30 -0300 (EST)
>From lua-l@tecgraf.puc-rio.br Wed Jul 28 20:27:03 1999
>From: Fred Bertsch <fb@anise.ee.cornell.edu>
>Is there a way to tell if two lua_Objects are equal from within C?
Sorry, not with the current API.
Something to consider for the next version.
>I have to
>figure out if they are in the same chunk of memory, but getting a pointer
>is obviously not supported by the standard API.
Right.
If you must go outside the API, then look at luaA_Address and luaO_equalval.
Something like (unofficial code ahead):
int ObjectEqual(lua_Object x, lua_Object y)
{
return luaO_equalval(luaA_Address(x),luaA_Address(y));
}
>The only technique I can come up with involves lua_dostring, but that's
>not particularly elegant.
I don't know whether you mean this (untested code ahead):
int ObjectEqual(lua_Object x, lua_Object y)
{
lua_Object eq;
int rc;
lua_beginblock();
eq=lua_getglobal("EQUAL");
if (lua_isnil(eq)) {
lua_dostring("function EQUAL(x,y) return x==y end; return EQUAL");
eq=lua_getresult(1);
}
lua_pushobject(x);
lua_pushobject(y);
lua_callfunction(eq);
rc=!lua_isnil(lua_getresult(1));
lua_endblock();
return rc;
}
For added "efficiency", you can lock the EQUAL function and save a reference
to it in a static var.
--lhf