[boost] Re: Re: [circular_buffer] comparison operators

From: Fredrik Blomqvist (fredrik_blomqvist_at_[hidden])
Date: 2005-04-20 16:04:56

Jan Gaspar wrote:
> Hi Fredrik,
>
> I'm attaching the discussion during the formal review
> regarding the comparison operators.
Thanks. I now remember reading some of those posts.
Did you reach a conclusion then? (Guess I have to dig the archives a bit...)

> into the reading, I'd like to say that my intension
> was to write STL compliant container nothing less or
> more and I'd like to stick with this.
That's a goal I fully support! But to my understanding
making this change wouldn't compromise compliance (?).
And as mentioned, several other boost components already
use this scheme, in this context most notably multi-index.

Regards
// Fredrik Blomqvist

> Subject: RE: [boost] Formal Review: Circular Buffer
> Date: Tue, 9 Mar 2004 09:44:34 -0800
> From: "Powell, Gary" <powellg_at_[hidden]>
> To: boost_at_[hidden]
>
>
> Shouldn't the comparison functions allow the types to
> differ? I mean
> don't they still lexigraphically compare as long as
> there is a comparison
> function F that a F b for each element exists
>
> circular_buffer<T, MyAlloc> x;
> circular_buffer<S, YourAlloc> y;
>
> bool b = x == y; for where the operator T == S is
> valid? And what does
> the allocator have to do with it?
>
> Therefore IMO, all of the comparison functions should
> change from
>
> template< typename T, typename Alloc>
> bool operator F ( circular_buffer<T, Alloc> &lhs,
>                  circular_buffer<T, Alloc> &rhs);
>
> to
>
> template< typename T1, typename Alloc1,
>          typename T2, typename Alloc2>
> bool operator F ( circular_buffer<T1, Alloc1> &lhs,
>                  circular_buffer<T2, Alloc2> &rhs);
>
>  Yours,
>  -Gary-
>
> -----------------------------------------------
>
>
> To: boost_at_[hidden]
> From: "Pavel Vozenilek" <pavel_vozenilek_at_[hidden]>
>
> Date: Tue, 9 Mar 2004 20:52:29 +0100
> Subject: [boost] Re: Formal Review: Circular Buffer
>
>
> Hmm, do you know a STL implementation/some container
> with this feature? It may be often bug to compare
> containers with
> different types.
>
> /Pavel
>
> -----------------------------------------------------
>
> Subject: RE: [boost] Re: Formal Review: Circular
> Buffer
> Date: Tue, 9 Mar 2004 13:55:15 -0800
> From: "Powell, Gary" <powellg_at_[hidden]>
> To: boost_at_[hidden]
>
>
> No, but just because the standard libraries scr*wed up
> is no reason to perpetuate the mistake.
>
> It's the rule of unexpected consequences.
>
> Is
> circular_buffer<int> x  = { 1, 2, 3};
> circular_buffer<short> y = { 1, 2 ,3};
>
> x == y ?? or not?
>
> Sure looks like it should work.
>
> The VTL library does it IMO correctly, allowing that
> if there is an operation T1 F T2, then V1 F V2
> compiles. Otherwise you just force the user to write
> what should be library code.
>