why some operators cannot be overloaded

[Bangalore]

Hi,
Can anybody explain , why some operators(::, ., .*, sizeof,?:) cannot
be
overloaded in C++?

Thanks

[benben]

> Hi,

Can anybody explain , why some operators(::, ., .*, sizeof,?:) cannot
be
overloaded in C++?

Thanks

http://www.research.att.com/~bs/bs_f...l#overload-dot

[Ian]

Bangalore wrote:

Hi,
Can anybody explain , why some operators(::, ., .*, sizeof,?:) cannot
be
overloaded in C++?

Because it makes no sense to do so.

Ian

[suresh]

Besides the sense can there be any other reasons??

Suresh

[Fabio Fracassi]

suresh wrote:

Ian wrote:

Because it makes no sense to do so.

Ian

well thats not entirely true. There are very good reasons to overload either
operator. and operator.* which is why allowing it is seriously considered
for the next version of C++

see: http://www.open-std.org/JTC1/SC22/WG...2004/n1671.pdf

It is usful to implement smart references or other forwarding handles.

Besides the sense can there be any other reasons??

Suresh

Well it is certainly a good policy not to allow things which make no sence.

The problem with all operator overloads is that it might lead to confusion,
if the overloaded operators work differently from the "normal" version.
In the case of an overloaded operator. There is for example no obvious way
to call member functions of the class which overloads the operator.

If you are interested in why c++ is as it is, you probably want to read
Design & Evolution of C++ by Bjarne Stroustrup.
HTH

Fabio