Re: [boost] [Booster] Or boost is useless for library developers

Subject: Re: [boost] [Booster] Or boost is useless for library developers
From: Gottlob Frege (gottlobfrege_at_[hidden])
Date: 2010-05-15 11:12:01

On Sat, May 15, 2010 at 10:53 AM, Artyom <artyomtnk_at_[hidden]> wrote:
>
>> OK, can I so something like the following?
>>
>> boost::shared_ptr<int> a(new int(0));
>> booster::shared_ptr<int> b = a;
>>
>> (replace shared_ptr with all the other boost-look-alike
>> classes)
>
> No you can't assign boost::shared_ptr to booster::shared_ptr as you
> can't assign std::tr1::shared_ptr to boost::shared_ptr
>
> But you can freely replace one with other as long as they consistent.
>

But that could then ripple through an entire codebase - 100Ks, most of
it not mine to change.

What might, instead, be possible is to make some bridge classes.

library.h:

inline boost::shared_ptr<int> some_api()
{
    boost::abi::shared_ptr<int> asp = some_api_abi(); // call the real function

    return boost::shared_ptr<int>(asp, boost::abi::deleter<int>);
}

***Or something like that***

Importantly, note that since this is in your h file, which I include,
I will get *my* version of shared_ptr returned from some_api().
It will be a wrapper around your shared_ptr, thus with extra overhead,
but at least it will work.

Basically your functions return a abi version of shared_ptr, which may
need to be pure interface, if you really want to be sure about abi:

template <typename T>
struct boost::abi::shared_ptr
{
    virtual void delete() = 0;
    virtual void add_ref() = 0;
    //...
};

Or maybe it is something else, but it is a simple bridge that you can
hopefully keep compatible for a number of years, and can be converted
to *my* shared_ptr.

Lather, rinse, repeat for other ABIs.  Yes, this may be cumbersome,
but no more than what you are already doing.

Tony