How to declare vector of generic template class

mzdude <>
Tue, 25 Nov 2008 13:31:08 -0800 (PST)
I'm trying to upgrade an existing design. It currently looks like
struct Foo {
   double x; // can be raw or rate
One is never quite sure what x contains. I would like to be more

So I thought I would do the following

struct Raw {
  Raw( double r, double scalar = 1.0 ) :
     raw(r) { scalar; }
  operator double () {return raw;}
    double raw;

struct Rate {
  Rate( double r, double scalar ) :
    rate( r / scalar ) {}
  operator double() {return rate;}
    double rate;

template< class T>
struct Foo {
  Foo(const T &x_) : x(x_) {}

  T x;
  bool operator==(const T &rhs); // details omitted

Now I can do things like
Foo<Raw> f1(Raw(500));
Foo<Rate> f2(Rate(500,.01));

What I would like to do is create a function that can return a vector
of either Raw or Rate objects. I know I can't overload a function
simply on return type.

int f();
float f(); // compile error

but I can do
template<typename T>
T f() {}

int x1 = f<int>();
float x2 = f<float>();

Right now what I have is

#define FooVector(T) std::vector<Foo<T> >

template<typename T>
FooVector(T) BuildList()
  FooVector(T) v;
  return v;

but I want to get rid of the macro.

Right now I'm struggling with the syntax of declaring a vector of
Foo objects.

What I want to do is
  // the following gives a compile error
  typedef template<typename T> std::vector<Foo<T> > FooVector<T>;

and ultimately

  template<typename T>
  FooVector<T> BuildList();

Is it possible? What is the correct syntax?


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