--- On Wed, 20/8/08, Daryle Walker wrote:

From: Daryle Walker Subject: Re: [Boost-users] Implementation question about boost::circular_buffer and allocator To: boost-users@lists.boost.org Date: Wednesday, 20 August, 2008, 10:37 PM On Aug 20, 2008, at 10:42 AM, Peter Barker wrote:

...

I've been going through the Boost libraries and encountered boost::circular_buffer. My question is not with the operation of Boost.Circular Buffer as-such, but about how the instantiation of it works without specifying the allocator.

The introductory example in the documentation(http://www.boost.org/ doc/libs/1_35_0/libs/circular_buffer/doc/ circular_buffer.html#briefexample) contains the following line:

// Create a circular buffer with a capacity for 3 integers. boost::circular_buffer<int> cb(3);

But looking at the header file base.hpp in the circular_buffer directory, we have the following:

template class circular_buffer { ......

};

The Alloc template parameter is not a default one, so I can't understand how we can instantiate cb in the example?

Apologies if this is not strictly boost-user related.

A forward declaration can provide defaults for template parameters. This is what is being done here, the main header is "boost/ circular_buffer.hpp" and its forward declaration, with default allocator, is at "boost/circular_buffer_fwd.hpp".

-- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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Daryle, Thank you very much - That was driving me crazy!