Re: [boost] RFC - lifetime management

From: Martin Schulz (Martin.Schulz_at_[hidden])
Date: 2007-09-19 08:22:59

> Still, the heap class is even more clear, easier to use and 
> easier to reason about. 
> I see the following benefits over 
> std::vector<boost::shared_ptr<void> >:
> 
>   1. More informative class and method names

Well, the name heap makes me think of a certain kind of memory 
management system. Probably a name like Keepalive_bucket would 
be clearer? 

>       Heaps should be non-copyable, vectors aren't.

Ok, that is a design choice and clearly influences the semantic.

>   5. Raw pointers can be handled more efficiently than shared_ptrs

But think of it - if that pointed-to object is in use by some other
means, 
it would be destroyed by the heap destructor nevertheless. Using shared 
pointers, the pointed-to objects are kept alive as long as either the
heap 
lives or as long they are used, whatever is longer. 

>   6. Better syntax. Repeating a long type name twice as with 
> boost shared_ptr can be tedious

Yes, I already noted that.

> Still I'm not sure if these points are enough to motivate a 
> new utility class. It's not exactly a killer app, even though 
> I find it very useful in MVC architectures (linking 
> controllers life time to views) and classes with lots of RAII 
> members. What do you think?

If ist helpfull to you, then go ahead and use & improve it. 

An (untested) wrapper class I would start with would be something like:

class Keepalive: private boost::noncopyable {
        Std::vector< boost::shared_ptr<void> > v;
public:
        template <typename T> void put(boost::shared_ptr<T> p) {
v.push_back(p); };
        template <typename T> void put(std::auto_ptr<T>& p) {
v.push_back(boost::shared_ptr<T>(p)); };
        template <typename T> void put(T *p) {
v.push_back(boost::shared_ptr<T>(p)); };
};

Does that solve your needs?

-- 
Dr. Martin Schulz (schulz_at_[hidden])
Software Engineer 
Synopsys GmbH 
Karl-Hammerschmidt-Str. 34
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