'__call' metamethod can be any callable object
Removed the restriction that a '__call' metamethod must be an actual
function.
diff --git a/ldo.c b/ldo.c
index 1a327ff..288aef1 100644
--- a/ldo.c
+++ b/ldo.c
@@ -348,18 +348,18 @@
/*
-** Check whether __call metafield of 'func' is a function. If so, put
-** it in stack below original 'func' so that 'luaD_call' can call
-** it. Raise an error if __call metafield is not a function.
+** Check whether 'func' has a '__call' metafield. If so, put it in the
+** stack, below original 'func', so that 'luaD_call' can call it. Raise
+** an error if there is no '__call' metafield.
*/
void luaD_tryfuncTM (lua_State *L, StkId func) {
const TValue *tm = luaT_gettmbyobj(L, s2v(func), TM_CALL);
StkId p;
- if (unlikely(!ttisfunction(tm)))
- luaG_typeerror(L, s2v(func), "call");
- for (p = L->top; p > func; p--)
+ if (unlikely(ttisnil(tm)))
+ luaG_typeerror(L, s2v(func), "call"); /* nothing to call */
+ for (p = L->top; p > func; p--) /* open space for metamethod */
setobjs2s(L, p, p-1);
- L->top++; /* assume EXTRA_STACK */
+ L->top++; /* stack space pre-allocated by the caller */
setobj2s(L, func, tm); /* metamethod is the new function to be called */
}
@@ -457,13 +457,13 @@
*/
void luaD_call (lua_State *L, StkId func, int nresults) {
lua_CFunction f;
- TValue *funcv = s2v(func);
- switch (ttypetag(funcv)) {
+ retry:
+ switch (ttypetag(s2v(func))) {
case LUA_TCCL: /* C closure */
- f = clCvalue(funcv)->f;
+ f = clCvalue(s2v(func))->f;
goto Cfunc;
case LUA_TLCF: /* light C function */
- f = fvalue(funcv);
+ f = fvalue(s2v(func));
Cfunc: {
int n; /* number of returns */
CallInfo *ci;
@@ -487,7 +487,7 @@
}
case LUA_TLCL: { /* Lua function */
CallInfo *ci;
- Proto *p = clLvalue(funcv)->p;
+ Proto *p = clLvalue(s2v(func))->p;
int narg = cast_int(L->top - func) - 1; /* number of real arguments */
int nfixparams = p->numparams;
int fsize = p->maxstacksize; /* frame size */
@@ -505,9 +505,9 @@
break;
}
default: { /* not a function */
+ checkstackp(L, 1, func); /* space for metamethod */
luaD_tryfuncTM(L, func); /* try to get '__call' metamethod */
- luaD_call(L, func, nresults); /* now it must be a function */
- break;
+ goto retry; /* try again with metamethod */
}
}
}
diff --git a/testes/calls.lua b/testes/calls.lua
index 56a12ae..739a624 100644
--- a/testes/calls.lua
+++ b/testes/calls.lua
@@ -151,6 +151,23 @@
print('+')
+do -- testing chains of '__call'
+ local N = 20
+ local u = table.pack
+ for i = 1, N do
+ u = setmetatable({i}, {__call = u})
+ end
+
+ local Res = u("a", "b", "c")
+
+ assert(Res.n == N + 3)
+ for i = 1, N do
+ assert(Res[i][1] == i)
+ end
+ assert(Res[N + 1] == "a" and Res[N + 2] == "b" and Res[N + 3] == "c")
+end
+
+
a = nil
(function (x) a=x end)(23)
assert(a == 23 and (function (x) return x*2 end)(20) == 40)
