Re: [boost] [intrusive] New version uploaded. Review Request.

From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2006-12-16 20:32:16

Pavel Vozenilek wrote:
> "Ion Gaztañaga" wrote:
> 
>> std::list::size":
>>
> One solution may be to provide  list::size()
> and have the size itself encoded as a signed integer.
> If the integer is >= 0 then the size() will return it.
> 
> After splice() the number will be set negative.
> Only the next size() call will go through the list
> and set the correct value again.
> For a typical list<> use the size() should
> get amortized to O(1).
> 
> Alexandrescu had discussed this few years ago
> in context of his YASLI library.

This can be an option. The downside is that size() is a const function 
and we should declare the size member as mutable. This converts a 
thread-safe function like size() to a non-thread safe one. But I agree 
that this can be a good solution. To avoid wasting a bit of the internal 
size integer, we could define size() as "this->size_ - 1", so 
this->size_ == 0 could represent unknown size and this->size_== 1 an 
empty list, this->size_ == 2 a list with just 1 element and so on.

Regards,

Ion