Re: What is wrong with this code ? (template class)

From:
 xtrigger303@gmail.com
Newsgroups:
comp.lang.c++
Date:
Mon, 03 Sep 2007 12:44:19 -0000
Message-ID:
<1188823459.967090.202980@d55g2000hsg.googlegroups.com>
On Sep 3, 1:19 pm, Anonymous <no.re...@here.com> wrote:

I have been trying to write a template class for a shared memory
container, over the last few days - but I keep getting numerous compiler
errors e.g:

Error: syntax error : identifier 'myStaticShmemAllocator<void>'
Error: 'AllocationPolicy' : undeclared identifier

Here is the truncated code below -

// template Header file
extern shared_memory static_shmem;
extern shared_memory dyn_shmem;

template <class T>
struct myStaticShmemAllocator
{
        static T* Allocate(const size_t blocksize, const bool zeroed=true)
        {
                return static_shmem.allocate(blocksize, zeroed);
        }

        static void DeAllocate(T *ptr)
        {
                if(ptr);
                        static_shmem.free(ptr) ;
        }

};

template <class T>
struct myDynamicShmemAllocator
{
        static T* Allocate(const size_t blocksize, const bool zeroed=true)
        {
                return dyn_shmem.allocate(blocksize, zeroed);
        }

        static void DeAllocate(T *ptr)
        {
                if(ptr);
                        dyn_shmem.free(ptr) ;
        }

};

template <class ValueType, template <class SharedMemoryType> class
AllocationPolicy= myStaticShmemAllocator<void> >
class static_shmemHashTable
{
        //Impl

};

//////// Code to test templates
struct MyStruct { int x; int y;};

int main(int argc, char* argv[])
{
    //implicit creation in static shmem (using dflt tplt arg)
    myShmemHashTable<MyStruct> a_static ;

    //explicit creation in static shmem
    myShmemHashTable<MyStruct, myStaticShmemAllocator<void> > a1_static ;

    //explicit creation in dynamic shmem
    myShmemHashTable<MyStruct, myDynamicShmemAllocator<void> > a_dynamic;

}- Hide quoted text -

- Show quoted text -


IMHO

template <class ValueType, template <class SharedMemoryType> class
AllocationPolicy= myStaticShmemAllocator<void> >
class static_shmemHashTable


this should become

template <class ValueType, template <class SharedMemoryType> class
AllocationPolicy= myStaticShmemAllocator >
class static_shmemHashTable

since it's a template< typename > class you should not specifiy the
templated typename or else you're giving a precise type not a
templated class

also the code down below should be stripped of <void> after
myStaticShmemAllocator and myDynamicShmemAllocator

Hope it helps.
FB

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