Re: Registries [2]

This seems to me to be the killer argument against having any implicit
imports of from-xxx converters.  No?

Daniel Wallin <[email protected]> writes:

> At 21:51 2003-07-30, David Abrahams wrote:
>>Daniel Wallin <[email protected]> writes:
>>
>> > At 21:45 2003-07-29, David Abrahams wrote:
>> >>Daniel Wallin <[email protected]> writes:
>> >>
>> >> > At 18:42 2003-07-29, David Abrahams wrote:
>> >> >>Daniel Wallin <[email protected]> writes:
>> >> >>
>> >> >> > I'm starting to doubt our motives for local registries altogether, I
>> >> >> > might be forgetting something or I might be drunk, but right now it
>> >> >> > seems to me that we'd be better off with only a global registry. I
>> >> >> > just can't think of any cases where there would be interest in hiding
>> >> >> > converters.
>> >> >> > This is quite a turnover for me, so if someone could convince me
>> >> >> > that there are benefits with local registries I'd be glad. ;)
>> >> >>
>> >> >>Consider: one extension is converting std::vector<int> into native
>> >> >>tuples, and another has exposed a class_ wrapper.
>> >> >
>> >> > Right, but that only justifies local registries of to_xxx converters.
>> >> > Any reason to have the from_xxx converters local as well?
>> >>
>> >>People like to put C++ code in the global namespace and might have
>> >>name collisions (?)
>> >
>> > Right, but with automatic importing they would be screwed anyway.
>>
>>Not if the automatic imports had a lower priority than the others, right?
>
> Yes, if the local converters with higher priority doesn't match and there
> is a true collision between different types. Consider:
>
> module X
>    struct A { std::string x };
>    converter from lua/python string -> A
>    f(const A&);
>
> module Y
>    struct A { int x };
>    converter from lua/python number -> A
>    f(const A&);
>
> Y.f("foo")
>
> ---
> Daniel Wallin
>
>
>
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-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com



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