Re: [boost] [parameter] Tutorial checked in

From: David Abrahams (dave_at_[hidden])
Date: 2005-07-20 13:35:27

Rob Stewart <stewart_at_[hidden]> writes:

> From: David Abrahams <dave_at_[hidden]>
>
> I'm not quoting much because it was a mess at my end.  Are you
> still using that utf-8 Gnus session?

Nope.

>> Yeah, that's about right.  No overload is needed -- I was just
>> addledwhen I wrote that.  The problem is, of course that while
>> the signatureabove is evocative, it is not the signature of any
>> real function we'llwrite.  I guess I could say, "here's what
>> the signature might be ifall arguments were required..."  Make
>> sense?
>
> Yes.
>
>>> let's see what your version is saying (to me).
>>> You say that there must be an "overloading taking its
>>> argument...."  Note the singular.  
>
>> Yes, note the singular!  Would it help if I wrote "taking
>> thatargument" or "taking its final argument?"
>
> But the last argument isn't taken by reference to const.  

Sure it is.
http://boost-consulting.com/boost/libs/parameter/doc/html/index.html#forwarding-functions
clearly shows it.

> Your current wording is:
>
>    To support an interface in which the last argument is passed
>    by keyword, there must be a depth_first_search overload taking
>    its argument by const reference.
>
> Since the overload you introduce immediately after that paragraph
> makes all but the last parameter be a reference to const, and the
> last be a reference to non-const, I'm left confused why my
> suggestions aren't right.

The foregoing section has the last argument passed
by const reference.  Then we say it's an out parameter, so

   ...That means the five-argument depth_first_search overload should
   really take its final argument by non-const reference.

Then we say

   On the other hand, ... there must be a depth_first_search overload
   taking its argument by const reference. 

Okay, I understand why that phrasing, followed by 

   The simplest solution in this case is to add another overload:

and the example taking a non-const reference is confusing.  I'll
shuffle things around.

Thanks.
-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com