Re: [boost] [type_erasure]any(const binding<Concept>&, ...) compile error

Subject: Re: [boost] [type_erasure]any(const binding<Concept>&, ...) compile error
From: Larry Evans (cppljevans_at_[hidden])
Date: 2012-07-26 12:21:23

On 07/26/12 09:57, Steven Watanabe wrote:
> AMDG
>
> On 07/26/2012 07:40 AM, Larry Evans wrote:
>> On 07/26/12 09:02, Steven Watanabe wrote:
>>> On 07/26/2012 05:29 AM, Larry Evans wrote:
>>>
>>> The concept doesn't contain anything that
>>> matches an argument of type value<_a>.
>>>
>> Then why isn't a similar compile error produced when b_any is
constructed?
>>
>
> This calls a different constructor which
> has different requirements.  Have you
> read the reference for any?  I tried
> to cover the constructors thoroughly.

My mistake.  I didn't notice:

http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/doc/html/boost/type_erasure/any.html#id2445089-bb

had:

  Concept must contain a matching instance of constructible.

However, in my defense, I couldn't see any reason why,
if:

   any<Concept,_a> a_any

can be created with static_map<Concept>, it couldn't be
created with a binding<Concept>; thus, I guess I just
glossed over the any.html#id2445089-bb doc.

BTW what *is* the reason for the restriction on the Concept in the
binding<Concept> CTOR.  It's obviously not needed for creating
an instance of AnyA with a value<_a>::type even when ConceptAB does
not "contain a matching instance of constructible".

>
>> A revised test driver(attached) uses double instead of
>> value<_a> and value<_b> and it still produces the same error.
>>
>
> Why would that make a difference?
>

None, now that I've read the doc's more closely.
Thanks for pointing me to which doc to read.
[snip]