error in reference qualifier

Question

Why I cant define this function,

int *clone() const &
{ 
    return new int(10); 
}

or

int x;
int *clone() const &&
{ 
    return new int(std::move(x)) ; 
}

I should be able to add const qualifier functions. Should I include any headers?

What Luchian Grigore said. Also, if x is a member variable and clone() a const method, std::move(x) would violate const-correctness if allowed to compile (because it would allow modifying x). — Medinoc, Jun 19 '13 at 07:48
and instead of returning a pointer to an int, its probably better to return the int itself — Enigma, Jun 19 '13 at 07:49
Its not the actual function, the actual is a big class,rather than int, I just simplified because problem is in qualifiers. — Tamim Addari, Jun 19 '13 at 08:02
@LuchianGrigore: well you should open the C++ standard then. cf my comment to doctorlove's reply. — v.oddou, Dec 09 '13 at 04:08
@v.oddou any C++ question can be answered with "open the C++ standard", so why bother posting on SO if you can't ask questions? — Luchian Grigore, Dec 09 '13 at 07:41

score 3 · Answer 1 · answered Aug 04 '13 at 14:56

I'm new to c++ and I am in the same error with you. I compiled the sample code, from C++ Primer 5th Edition, which described the reference qualifier. However, my GNU compiler showed me error. I suppose that current compilers do not support this new feature introduced in C++11. And it seems not many people know this because very few information can be found on the Internet. Maybe later compilers will support this feature.

Many c++11 features haven't been supported... I've met some before.

This is part of the sample code, similar to yours:

Foo sorted() &&;
Foo sorted() const &

score 0 · Answer 2 · answered Jun 19 '13 at 07:50

0

Because any qualifier after function name applies to this pointer. if you want to make constant this pointer
you should just do overloading by : int *clone() const

answered Jun 19 '13 at 07:50

Anand Rathi

746
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So when do I use reference qualifiers? – Tamim Addari Jun 19 '13 at 08:00
@TamimAdDari after function name? NEVER – kassak Jun 19 '13 at 08:05
@kassak is right you cant overload function using eference qualifiers AFTER the funcvtion name , that is this pointer – Anand Rathi Jun 19 '13 at 08:08

score 0 · Accepted Answer · edited May 23 '17 at 12:22

0

You can use the r-value reference on parameters, for example in a move assignment or move constructor. It seems clang has been trying an extension called 'called "rvalue reference for *this"', but I suggest you work through the move constructors and assignment operators first.

edited May 23 '17 at 12:22

Community

1
1

answered Jun 19 '13 at 09:06

doctorlove

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C++11 clearly specifies the ref-qualifier on functions. see `8.3.5 [dcl.fct]`. [gcc support](http://gcc.gnu.org/ml/gcc-patches/2013-04/msg00024.html). You all need to give OP a break. – v.oddou Dec 09 '13 at 04:07

error in reference qualifier

3 Answers3