Blitz Library Strange Initialization

I have been trying to figure out how the Blitz numeric library was able to get commas to initialize Vectors and Matrices. For example,

Code:

---

TinyMatrix<double, 2, 2> m;
m = 1, 2, 3, 4;

---

is perfectly valid. I have looked through the source, but I don't see any operator,(T_numtype n) in there. What did he do?

I figured it out! What it does is in the operator= overload for TinyMatrix it returns an object that has operator,(T_numtype) overloaded. That object takes as an argument an iterator to TinyMatrix. The operator, simply increments the iterator each time a new number is encountered, pretty sneaky. I made an ultra simple example utilizing the same trick (without iterators) if anyone here is curious.

Code:

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class ListInit
{
 int* parr;
public:
 ListInit() { parr = NULL; }
 ListInit(int* parrz) { parr = parrz; }
 ListInit& operator,(int num) {
  *parr = num;
  parr++;
  return *this;
 }
};

class Array
{
 int arr[3];
public:
 Array()
 {
  arr[0] = 0;
  arr[1] = 0;
  arr[2] = 0;
 }
 
 Array(int x1, int x2, int x3)
 {
  arr[0] = x1;
  arr[1] = x2;
  arr[2] = x3;
 }
 
 ListInit operator=(int x)
 {
  arr[0] = x;
  return ListInit(&arr[1]);
 }
 
 void Print()
 {
  cout << arr[0] << ", " << arr[1] << ", " << arr[2] << endl;
 }
};

int main(int argc, char *argv[])
{
 Array x;
 x = 1, 2, 3;
 x.Print();
 return EXIT_SUCCESS;
}

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Boost has a library completely dedicated to this kind of assignment. It is called "assign." It seems pretty interesting. Thanks for at least looking.

thats interesting... wuld be good for sizing multidimensionals.
but there is this design issue here what would be best to use?
maybe Array.Size = 1, 2, 3; or Array.Size = [1][2][3]; (if it wuld be possible) or Array.Size[1][2][3] or ()'s

Something like Array.SetSize[1][2][3] should be possible.

yes but at design what would be better? Array.Size = 1, 2, 3; or Array.Size[1][2][3];