Constructor for a no-named struct

Question

I have a class something like that:

template <class T>
class bag
{
public:

private:
 typedef struct{void* prev; struct{T item; unsigned int count;} body; void* next;}* node; 
 typedef struct{
  node operator->() { return current; }
  operator(){;} // <- i can not do that, right?

 private:
  node current;
 } iterator;
//...
};

So, how to write a constructor for the bag::iterator?

@Peter G.: not anonymous, this is an "unnamed class defined in a typedef declaration" `7.1.3/5` — Cubbi, Oct 05 '10 at 15:22

score 6 · Accepted Answer · answered Oct 05 '10 at 15:19

6

Make some nice name for it :-)

typedef struct NoName1 {void* prev; NoName1(){}; struct NoName2{T item; unsigned int count; NoName2() {}} body; void* next;}* node;

EDIT: LOL sorry, wrote it for the wrong one, but the principle is the same :-)

answered Oct 05 '10 at 15:19

Šimon Tóth

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Cubbi · Answer 2 · 2010-10-05T15:42:11.430

There is no way to write a constructor for bag::iterator because iterator is a typedef name, which are prohibited from being used as constructor names:

14882:2003 12.1/3

a typedef-name that names a class shall not be used as the identifier in the declarator for a constructor declaration.

There is even an example in the standard, although in a different paragraph, 7.1.3/5:

typedef struct {
    S();         //error: requires a return type because S is
                 // an ordinary member function, not a constructor
} S;

You will have to give that struct a name, if you want a user-defined constructor. The typedef struct { } name; style of programming is usually discouraged by C++ style guides anyway, in favor of struct name { };.

Constructor for a no-named struct

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