Why am I getting "C stack overflow"?
I’m creating my own Vector3 class just for fun, but I am having problems with it.
Here is my code
01 | local Vector3 = {}; |
02 | local mt = { |
03 | __index = Vector3, |
04 | __metatable = "This metatable is locked", |
05 | __newindex = function(t, k, v) |
06 | rawset(t, k, nil); |
07 | error(k .. " is not a valid member of Vector3", 2); |
08 | end, |
09 | __mul = function(op1, op2) |
10 | if (rawequal(type(op1), "table") and rawequal(type(op2), "table")) then |
11 | return Vector3.new(op1.X*op2.X, op1.Y*op2.Y, op1.Z*op2.Z); |
12 | end |
13 | |
14 | if (rawequal(type(op2), "number")) then |
15 | return Vector3.new(op1.X*op2, op1.Y*op2, op1.Z*op2); |
16 | end |
17 | end, |
18 | __tostring = function(t) |
19 | return t.X .. ", " .. t.Y .. ", " .. t.Z; |
20 | end, |
21 | __unm = function(t) |
22 | return Vector3.new(-t.X, -t.Y, -t.Z); |
23 | end, |
24 | __div = function(op1, op2) |
25 | if (rawequal(type(op1), "table") and rawequal(type(op2), "table")) then |
26 | return Vector3.new(op1.X/op2.X, op1.Y/op2.Y, op1.Z/op2.Z); |
27 | end |
28 | |
29 | if (rawequal(type(op2), "number")) then |
30 | return Vector3.new(op1.X/op2, op1.Y/op2, op1.Z/op2); |
31 | end |
32 | end, |
33 | __add = function(op1, op2) |
34 | return Vector3.new(op1.X + op2.X, op1.Y + op2.Y, op1.Z + op2.Z); |
35 | end, |
36 | __sub = function(op1, op2) |
37 | return Vector3.new(op1.X - op2.X, op1.Y - op2.Y, op1.Z + op2.Z); |
38 | end |
39 | }; |
40 |
41 | function Vector3.new(x, y, z) |
42 | local self = {}; |
43 | self.X = x or 0; |
44 | self.Y = y or 0; |
45 | self.Z = z or 0; |
46 | self.Magnitude = math.sqrt(x^2 + y^2 + z^2); |
47 | setmetatable(self, mt); |
48 | self.Unit = self/self.Magnitude; |
49 | return self; |
50 | end |
51 |
52 | local myVector3 = Vector3.new(10, 20, 30); |
53 |
54 | print( |
55 | myVector3, |
56 | -myVector3, |
57 | myVector3*2, |
58 | myVector3/2, |
59 | myVector3 + Vector3.new(1, 1, 1), |
60 | myVector3 - Vector3.new(1, 1, 1), |
61 | myVector3*Vector3.new(2, 2, 2), |
62 | myVector3/Vector3.new(2, 2, 2) |
63 | ); |
(I get this error on line 48, which is in the Vector3.new constructor, which is self.Unit = self/self.Magnitude;
From what I understand, this “C stack overflow” would only occur if you invoked the metamethod within the function. Here is an example of what I mean:
1 | local t = {}; |
2 | setmetatable(t, {__index = function(t, k) |
3 | return t[k]; |
4 | end}; |
t[k] invokes __index again, thus calling that function again, and again: it is a circle.
I am not dividing my table within the __div function? If I am, can someone show me where? Or can other things cause this “C stack overflow” as well that I am doing?
Everything else seems to work just fine.
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2 answers
You’ll need to do:
1 | function mt:__index(index) |
2 | if index:lower() == 'unit' then |
3 | return self/self.Magnitude |
4 | end |
5 | end |
I found the issue:
It was in __div
1 | __div = function(op1, op2) |
2 | if (rawequal(type(op1), "table") and rawequal(type(op2), "table")) then |
3 | return Vector3.new(op1.X/op2.X, op1.Y/op2.Y, op1.Z/op2.Z); |
4 | end |
5 |
6 | if (rawequal(type(op2), "number")) then |
7 | return Vector3.new(op1.X/op2, op1.Y/op2, op1.Z/op2); |
8 | end |
9 | end |
I was calling Vector3.new within its definition, thus causing a stack overflow.
I also have a solution:
1 | self.Unit = { |
2 | X = self.X/self.Magnitude, |
3 | Y = self.Y/self.Magnitude, |
4 | Z = self.Z/self.Magnitude |
5 | }; |
6 | |
7 | setmetatable(self, mt); |
8 | setmetatable(self.Unit, mt); |
pasting code in this is a huge pain eryn pls fix