Test case:
#include <boost/shared_ptr.hpp>
using namespace boost;
template <typename typ1> class cData {
public:
template <typename T> T As() { } // As
};
template <typename D, typename T>
class cTaggedData : public cData<D> {
public:
};
template <typename D, typename T>
class cAttr : public cTaggedData<D,T> {
public:
};
template <typename D, typename T>
class cNode : public cTaggedData<D,T> {
public:
shared_ptr< cAttr<D,T> > RetAttr() { }
template <typename X> X MyAs(T t, X& x) {
#line 100
shared_ptr< cAttr<int,int> > attr1; attr1->As<int>(); // works
#line 200
shared_ptr< cAttr<D,T> > attr2; attr2->As<int>(); // FAILS
#line 300
shared_ptr< cAttr<int,int> > attr3; attr3->As<X>(); // works
#line 400
shared_ptr< cAttr<D,T> > attr4; attr4->As<X>(); // my goal, FAILS
} // As
};
/*
gives:
x.cpp: In member function 'X cNode<D, T>::MyAs(T, X&)':
x.cpp:200: error: expected primary-expression before 'int'
x.cpp:200: error: expected `;' before 'int'
x.cpp:400: error: expected primary-expression before '>' token
x.cpp:400: error: expected primary-expression before ')' token
*/
int main() { }
How to fix thoes two errors? Especially the 400 one? 2 1580
* Rafał Maj Raf256: Test case:
#include <boost/shared_ptr.hpp>
using namespace boost;
template <typename typ1> class cData { public: template <typename T> T As() { } // As };
template <typename D, typename T> class cTaggedData : public cData<D> { public: };
template <typename D, typename T> class cAttr : public cTaggedData<D,T> { public: };
template <typename D, typename T> class cNode : public cTaggedData<D,T> { public:
shared_ptr< cAttr<D,T> > RetAttr() { } template <typename X> X MyAs(T t, X& x) { #line 100 shared_ptr< cAttr<int,int> > attr1; attr1->As<int>(); // works #line 200 shared_ptr< cAttr<D,T> > attr2; attr2->As<int>(); // FAILS #line 300 shared_ptr< cAttr<int,int> > attr3; attr3->As<X>(); // works #line 400 shared_ptr< cAttr<D,T> > attr4; attr4->As<X>(); // my goal, FAILS } // As
}; /* gives:
x.cpp: In member function 'X cNode<D, T>::MyAs(T, X&)': x.cpp:200: error: expected primary-expression before 'int' x.cpp:200: error: expected `;' before 'int' x.cpp:400: error: expected primary-expression before '>' token x.cpp:400: error: expected primary-expression before ')' token */
Using #line is a really good idea, I'll steal that for my own examples!
Anyway,
#line 100
shared_ptr< cAttr<int,int> > attr1; attr1->As<int>(); // works
#line 200
shared_ptr< cAttr<D,T> > attr2; attr2->template As<int>(); // works
#line 300
shared_ptr< cAttr<int,int> > attr3; attr3->As<X>(); // works
#line 400
shared_ptr< cAttr<D,T> > attr4; attr4->template As<X>(); // works
The problem is that you're using the name As which depends on the
template paramters D and T, and the compiler knows nothing about what As
could be (especially, that it would be a template) for any specific D and T.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Alf P. Steinbach wrote: Using #line is a really good idea, I'll steal that for my own examples!
Nice :)
#line 100 shared_ptr< cAttr<int,int> > attr1; attr1->As<int>(); // works #line 200 shared_ptr< cAttr<D,T> > attr2; attr2->template As<int>(); // works #line 300 shared_ptr< cAttr<int,int> > attr3; attr3->As<X>(); // works #line 400 shared_ptr< cAttr<D,T> > attr4; attr4->template As<X>(); // works
The problem is that you're using the name As which depends on the template paramters D and T, and the compiler knows nothing about what As could be (especially, that it would be a template) for any specific D and T.
#line 200
shared_ptr< cAttr<D,T> > attr2; attr2->template As<int>();
#line 400
shared_ptr< cAttr<D,T> > attr4; attr4->template As<X>();
is the finall solution then :)
I was quite close, tried to add, in the main class { } cNode scope
using cAttr<D,T>::As<>;
g++ warned me:
note: use 'cAttr<D, T>::template As' to indicate that it is a template
only I put it in wrong place
btw, it seem to compile fine on newer MSVC even without the template
--
Wymiana starych układów... na nowe układy - prawie jak walka z korupcja.
Walka z wychowaniem seksualnym i erotykÄ… - prawie jak walka z patologiÄ….
PiS - prawie jak prawo i sprawiedliwość... Prawie. Prawie robi różnicę.
Myśl. Głosuj rozsądnie. Nie na tanie hasła. // Rafał Maj Raf256 This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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