Re: [boost] [circular_buffer] some comments and suggestions

From: Jan Gaspar (jano_gaspar_at_[hidden])
Date: 2008-01-21 11:28:07

#1
I don't agree. I tried to design the circular_buffer as close as possible to the other std containers. Suppose the cirular_buffer does not allocate anything on construction - this means when you insert an element to the buffer, it will not be inserted because the capacity is 0. I think this is unnatural for std containers. On the other hand there is a note in the documentation that you should avoid using this constructor: "This constructor has been defined only due to compatibility with the STL container definition. Avoid using it because it may allocate very large amount of memory."
 
#2
Agree with is_linearized(), I don't agree with special iterator - I cannot see the point - just use pointers as you mentioned.
 
#3
Yes, maybe in the next version. What would be the method signature?
 
Regards,
 
Jan


----- Original Message ----
From: Thorsten Ottosen <thorsten.ottosen_at_[hidden]>
To: "boost_at_[hidden]" <boost_at_[hidden]>
Sent: Monday, 21 January, 2008 11:40:23 AM
Subject: [boost] [circular_buffer] some comments and suggestions

Hi Jan,

#1
I was browsing through the docs in trunk. First I noticed that the
default constructor has the follwoing postcondition:

  capacity() == max_size() && size() == 0

I find that somewhat unfortunate that it allocates a huge amount of 
memory. It seems to me that it is too easy to do that by coincidence.
The usual rule for std containers is to never allocate by default and 
anticipate a call to reserve() or the first element. It also seems to me 
that this will create problems when the container is used in containers 
that might use default construction.

#2
I think it would be useful to add a predicate called is_linearized(), so 
one can check if this property holds. Also, if this do hold, I should be
able the get fast iterators to this linear segment, perhaps by calling 
.base() on the iterators which then simply return a pointer
(I know I can get the pointers by array_one(), but I would more often 
need the iterators).

#3
I think it would be useful to add rotate() as a member function. AFAICT, 
it can in many times (if not all) be much faster than std::rotate() 
because it can simply move a few elements and then simply adjust the 
iterators.

-Thorsten
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