lua-users home
lua-l archive

Re: Strange Lua behavior with __eq return values

[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index] [Thread Index]


Leo Razoumov wrote:
On 11/20/08, Matthew Paul Del Buono <delbu9c1@erau.edu> wrote:
Hi list,
[..snip..]
 I see that it should be executing the line "return (h(op1, op2))" but that's not what I seem to get in response. I would expect "true" to be the result if the manual stated "return not not (h(op1, op2))" but it doesn't.
 Is this a manual problem, a Lua problem, or am I missing something?
Apparently, the manual and the actual Lua implementation do differ.
In the function "luaV_equalval" defined in "lvm.c" the last two line are
 callTMres(L, L->top, tm, t1, t2); /* call TM */
 return !l_isfalse(L->top);
that essentially mean "return not not (h(op1, op2))" as you correctly guessed.
It is different from the pseudo-code in the manual. I would suggest to
correct the manual.
luaV_equalval needs to return a boolean 0 or 1 for comparison with the boolean value in field A in the OP_EQ opcode implementation. This is a straight int comparison, so a 0 or 1 value is mandatory. So in the manual, the pseudo-code's return type of boolean is implicit.
--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia

AltStyle によって変換されたページ (->オリジナル) /