Re: [boost] Sealed C++ class (error description)

From: Tom Honermann (tom.honermann_at_[hidden])
Date: 2006-04-07 21:55:48

Presumably, identity<T>::type would be a typedef which would also be 
invalid:

Section 7.1.5.3 paragraph 2 of Standard C++:

    3.4.4 describes how name lookup proceeds for the /identifier/ in an
    /elaborated-type-specifier/. ... If the /identifier/ resolves to a
    */typedef-name/* or a *template /type-parameter/*, the
    /elaborated-type-specifier/ is ill-formed. [/Note/: this implies
    that, within a class template with a template /type-parameter/ T,
    the declaration

        friend class T;

    is ill-formed. ] 

Tom.

Felipe Magno de Almeida wrote:

>On 4/7/06, Anthony Williams <anthony_w.geo_at_[hidden]> wrote:
>  
>
>>Vladislav Lazarenko <snail_at_[hidden]> writes:
>>    
>>
>
>[snipped]
>
>  
>
>>Unfortunately the declaration "friend typename T", is not legal. It might
>>happen to work on current releases of Microsoft compilers, but that's a bug in
>>the compiler.
>>    
>>
>
>Is
>
>friend typename identity<T>::type;
>
>also illegal?
>
>  
>
>>Anthony
>>--
>>Anthony Williams
>>Software Developer
>>Just Software Solutions Ltd
>>http://www.justsoftwaresolutions.co.uk
>>    
>>
>
>--
>Felipe Magno de Almeida
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>  
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