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Subject: Re: [boost] [concept_check] Some issues
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-11-25 12:07:22

Robert Kawulak wrote:
> I've spotted some problems when playing with BCCL:
> - The implementation of assignable_archetype defines private
> default and copy constructors, so for example
> assignable_archetype<copy_constructible_archetype<>> will not
> actually be copy constructible. The same for
> convertible_to_archetype and convertible_from_archetype, but
> additionally with copy assignment. Is this by purpose?

I should think that's by design. The archetypes are to validate a particular concept checking class, so a copyable or default constructible archetype for Assignable would be wrong. Are archetypes are supposed to be composable? Even if so, not all combinations are possible.

> - copy_constructible_archetype defines public default
> constructor - again, am I overlooking something or it should
> not be there?

I wouldn't think so.

> - Function and predicate archetypes also seem to provide too
> wide interface (they are copy constructible and assignable).

Since you're asking, and I haven't checked to verify it, I presume that those operations are not part of the corresponding concepts. If so, then I agree they should not be available.

> Additionally, they don't allow for archetypes chaining since
> they lack the Base parameter (with the only exception of
> binary_predicate_archetype - why the inconsistency?)

Are they supposed to be generally chainable?

> - Apart from the provided function object concepts and
> archetypes it seems it would be useful to have a general
> Callable concept and the corresponding callable_archetype,
> parameterised with the types of arguments and return value.
> Wouldn't it be valuable to add them?

That seems plausible and useful.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP


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