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Jaap Suter · Guest

Hi,

I have a smartpointer type, where I want to perform an operation before and
after each dereference. I tried the following:

template < class T >
class sptr
{
public:

proxy operator -> () { return proxy( mPtr ); }

private:
class proxy
{
proxy( T* t ) : mPtr( t ) { prefix_op(); }
~proxy() { postfix_op(); }

T* operator -> { return mPtr; }
private:
T* mPtr;
};

T* mPtr
};

This works on MSVC but fails on GCC 2.9.x, because of different lifetimes of
objects. On MSVC the following code:

sptr< bar > p( ... );
p->foo();

does the following:

prefix_op();
bar::foo();
postfix_op();

whereas on GCC, the following happens:

prefix_op();
postfix_op();
bar::foo();

which is bad because the postfix shuts something down that is needed in
bar::foo();. I was wondering whether the standard says anything about the
lifetime of the proxy object in the code above. Futhermore, is there a way
to achieve what I am trying to achieve?

Regards,

Jaap Suter

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Marco Manfredini · Guest

Jaap Suter wrote: