Implementation question about boost::circular_buffer and allocator
Hello, 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_buffe...) 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 T, class Alloc> 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. Regards, Jim
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 T, class Alloc> 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
--- On Wed, 20/8/08, Daryle Walker <darylew@hotmail.com> wrote:
From: Daryle Walker <darylew@hotmail.com> 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 T, class Alloc> 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!
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Peter Barker