Re: [Boost-users] Pointer in function parameter?

From: Manuel Jung (gzahl_at_[hidden])
Date: 2007-05-08 11:16:02

Meryl Silverburgh wrote:
> On 5/8/07, Nat Goodspeed <ngoodspeed_at_[hidden]> wrote:
>> > -----Original Message-----
>> > From: boost-users-bounces_at_[hidden] [mailto:boost-users-
>> > bounces_at_[hidden]] On Behalf Of Meryl Silverburgh
>> > Sent: Tuesday, May 08, 2007 9:32 AM
>> > To: boost-users_at_[hidden]
>> > Subject: [Boost-users] Pointer in function parameter?
>> >
>> > vector< boost::shared_ptr<A> >  aVector;
>> >
>> > aFunc(aVector[0]) ; // just call a
>> >
>> > My question is should I change the function parameter of aFuncion from
>> > this:
>> >
>> > void aFunc(A* aPtr) {
>> > // access aPtr
>> > }
>> >
>> > to this:
>> >
>> > void aFunc(shared_ptr<A> aPtr) {
>> > // access aPtr
>> > }
>>
>> [Nat] Looks reasonable to me... I believe the docs say that it's
>> conventional to pass shared_ptr by value rather than (e.g.) const
>> reference so that the ref count will be adjusted properly.
> 
> Thanks. But what if I have
> 
> void aFunc(const A* aPtr) {
>  // access aPtr
>  }
> 
> should I change it to
> 
> void aFunc(const shared_ptr<A> aPtr) {
>  // access aPtr
>  }
Hi,

I would say: Yes, you should change it to the 2nd variant, BUT sometimes the
first variant is also ok.

You could use the 1st variant, but you will loose your benefit from
shared_ptr<>. You have to gurantee that the shared_ptr<> is not destroyed
while you are running aFunc().

So use the 2nd variant and choose the safe way.
I hope it is a little more clear to you now! 
Much fun
Manuel Jung

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