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From: clamage@Eng.Sun.COM (Steve Clamage)
Newsgroups: comp.lang.c++,comp.std.c++
Subject: Re: friends and local classes
Date: 22 Jan 1995 03:47:40 GMT
Organization: Sun Microsystems Inc., Mountain View, CA
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Viktor Yurkovsky <n4mation@panix.com> writes:

>jgealow@mtl.mit.edu (Jeffrey C. Gealow) wrote:
>>
>> Should a local class assume the friendships of the enclosing function?  
>> For example, consider the following:
>> 
>> class X {
>>   int i;
>>   friend int f(X);
>> };
>> 
>> int f(X o)
>> {
>>   struct local {
>>     static int l(X o) { return o.i; }  // error?
>>   };
>>   return local::l(o);
>> }
>> 
>> Should struct local, declared within the definition of f(X), act 
>> as a friend of class X?
>
>Seems to me that friend applies to the entire function, and anything
>inside that function should have access.

No.

No function is a friend of a class unless that class so declares
that function. Since local::l is not declared to be a friend of X,
it isn't a friend.  (It cannot be so declared because it isn't visible.)

Friendship is not inherited, isn't implicit, and cannot be asserted.

See ARM 11.4.

N.B.: A shorthand notation allows all the member functions of a
class to be simultaneously declared to be friends of another
class. That notation is not used here (and can't be used, because
the class "local" isn't visible).

--
Steve Clamage, stephen.clamage@eng.sun.com