Initializing a static element of a template class

[Tom]

Please consider the following code snippet:

template<class T> class lifo
{ public:
static T* Anchor;
T* Next;
};

typedef lifo<int> intlifo;
int* lifo<int>::Anchor = NULL; // error: too few parameter lists
int* intlifo::Anchor = NULL; // error: too few parameter lists

What do i have to do in order to initialize Anchor of lifo<int> ?
Where is a parameter list required ?

(sorry if this is a stupid question; it's the first time i play around with
templates...)

Thanks,

Tom

 

[Vladimir Jovic]

Please consider the following code snippet:

template<class T> class lifo
{ public:
static T* Anchor;
T* Next;
};

typedef lifo<int> intlifo;
int* lifo<int>::Anchor = NULL; // error: too few parameter lists
int* intlifo::Anchor = NULL; // error: too few parameter lists

It is not clear what you tried to do here, and where you placed last 3
lines. See http://www.parashift.com/c++-faq-lite/how-to-post.html#faq-5.8

What do i have to do in order to initialize Anchor of lifo<int> ?
Where is a parameter list required ?

You have to fix the definition of the Anchor pointer, something like this:

template< class T >
T* lifo< T >::Anchor = NULL;

This example works:

template<class T> class lifo
{
public:
static T* Anchor;
T* Next;
};
template< class T >
T* lifo< T >::Anchor = NULL;

int main ()
{
lifo< int > aaa;
int bbb = 3;
aaa.Next = &bbb;
int ccc = 3;
lifo< int >::Anchor = &ccc;
a.Anchor = &ccc;
}

 

[Tom]

It is not clear what you tried to do here, and where you placed last 3
lines. See http://www.parashift.com/c++-faq-lite/how-to-post.html#faq-5.8

You're absolutely right, i was too fast with copy & pasting. I will improve
next time.

You have to fix the definition of the Anchor pointer, something like this:

template< class T >
T* lifo< T >::Anchor = NULL;

ok, i see i misunderstood something fundamental about templates...

This example works:

template<class T> class lifo
{
public:
static T* Anchor;
T* Next;
};
template< class T >
T* lifo< T >::Anchor = NULL;

int main ()
{
lifo< int > aaa;
int bbb = 3;
aaa.Next = &bbb;
int ccc = 3;
lifo< int >::Anchor = &ccc;
a.Anchor = &ccc;
}

Thanks a lot, Vladimir