From: Beman Dawes (bdawes_at_[hidden])
Date: 2003-10-21 20:08:05
At 04:22 PM 10/21/2003, Pavol Droba wrote:
>Following the complaints about some missing information about the
>library, pointed out by Beman, I'd like to explain here in more detail
>concepts used in the library.
>Unlike the STL algorithm library, which is iterator-oriented, string_algo
>has adopted a Container as a basic concept used for arguments.
>However, STL specification of a container if too strong. On many places,
>simplified version of the Container concept is sufficient.
>We use the name InputContainer for it.
> typedef ... value_type;
> typedef ... size_type;
> typedef ... iterator;
> typedef ... const_iterator;
> typedef ... difference_type;
> iterator begin();
> const_iterator begin() const;
> iterator end();
> const_iterator end() const;
> size_type size();
> bool empty();
>These properties are exactly the properties the STD Container concept,
>except of construction/destuction method, and swap.
OK, good. This is starting to fill in the missing pieces. Presumably you
will change the name of template parameters to InputContainerConcept where
Specifying the types and operations as member signatures is precise, but is
really overspecification. The Standard Library approach of specifying a
requirements table is precise, yet leaves the implementor a bit of wiggle
room to meet the specification. I don't think it matters at this stage, but
others may have stronger opinions.
The Standard Library clause 23.1 has five or so requirements tables
(Container, Reversible Container, Sequence, etc). Where the docs talk about
"the Std Container concept", it would be clearer if they said "the Standard
Library Container requirements table 65 in section 23.1" or something
similar. That's a bit pedantic, but more precise.
>This concept allows to access the values contained in the container,
>without altering the state of the container itself. It means, [that] it
>is not possible to change, what elements are contained by this container.
>It is sufficient for those arguments in algorithms with are not altered
>(i.e. immutable arguments)
Presumably you will then have a similar concepts for algorithms needed
erase or other members? That will resolve the current confusion caused by
using the same name (ContainerT) for template parameters with different
>container_traits, one of the core facilities defined in theis library,
>wraps this concept,
>and allows to access some of legacy C structure (C-arrays and string)
>iterator_range also implements this concept for a pair of iterators.
OK, as soon as it is known exactly what algorithms require this concept
(rather than EraseableContainer (or whatever), then it becomes possible to
understand which algorithms would work with C style arrays or other
almost-containers, and as many other gradations of functionality as there
are requirement concepts.
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk