[boost] shared_ptr: non-temporary ctor arguments

From: marchetti alessio (alessio_marchetti_at_[hidden])
Date: 2002-04-02 03:01:17

hi,

I was looking at usage patterns of the shared_ptr
template and noticed that most of the times it only
makes sense to create smart pointer objects from
un-named (temporaries) naked pointers:

  shared_ptr<int> cp (new int);

The following idiom creates confusion (the ip variable
is not used after the ctor call):

  int * ip = new int;
  shared_ptr<int> cp ( ip );

The first idiom promotes better encapsulation: do you
think that forcing this usage patterns through
interface would make sense?

It's possible to do that by changing the ctor:

    explicit shared_ptr(T * p = 0): px(p), pn(p,
deleter())
    {
    }

to 

    explicit shared_ptr(T * const &p = 0): px(p),
pn(p, deleter())
    {
    }

and by adding an additional dummy ctor:

    explicit shared_ptr(T * &p): px(p), pn(p,
deleter())
    {
     
shared_ptr_ctor_needs_temporary_actual_parameter;
    }

This change of course breaks source compatibility...

Alessio Marchetti

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