Passing template class by reference

[Jonathan Wakely]

On 3 February 2010 23:07, Minhaj Ahmed wrote:
> How do you pass a template class object by reference? As an example:

This is off-topic for this mailing list, please take your question to
the gcc-help mailing list or a forum about C++

> Say we have a namespace util  and
>
> Namespace NewName
> {
> Class A
> {
>                SomeRoutine(util::CSomeUtilClass<CDataWrapperClass>
> &msg);

This function is missing a return type.

> };
> }
>
> Now when I call this method in a cpp file gcc complains that
> "error: with
> NewName::A::SomeRoutine(util::CSomeUtilClass<CDataWrapperClass>&)'
> And
> Error: no matching function for call to
> 'NewName::A::SomeRoutine(util::CSomeUtilClass<CDataWrapperClass>&)'
>
> Any idea how I can get around this?  I can remove the '&' from method
> and have it compile just fine!  Any help would be greatly appreciated...

I would guess you're passing a temporary or a const obejct which
cannot bind to the non-const reference.

> Also I've another strange problem with nested classes:
>
> So let say we have
>
> Class SemaphoreC
> {
> ...
> };
>
>
> Class data
> {
> ...
> };
>
> Namespace util
> {
>
>        tempate <class T>
>        Class SmartPtr
>        {
>        ...
>        };
>
>
>        template <class T>
>        class someTemplate
>        {
>        Public:
>                GetSem(){return m_sem);

Again, you're missing a return type - this isn't valid C++.

All the uppercase letters don't help either.


>        Private:
>                SemaphoreC m_sem;
>        };
>
> }
>
> class A
> {
>        Class Nested
>        {
>                Class A *a_ptr;
>        };
>
>        Private:
>        TrytogetSem();
>        util::someTemplate< util::SmartPtr<data> > var;
> };
>
> Now when the GetSem is called from A::TrytogetSem() ie.
>
> A::TrytogetSem()
> {
>                Declared in class Nested    declared in class A
> member of someTemplate
>                        |                               |
> |
>                        |                               |
> |
>  SemaphoreC s = a_ptr->                        var.
> GetSem();
>
> }
>
> And gcc complains that it's unable to convert void * to LONG?  I can
> declare 's' as void * and the error disappears

I can't read the code above, but as I said, please ask this in a more
appropriate forum.

Jonathan