Re: [boost] [bitstream] Copy stream buffer or pass pointer?

Subject: Re: [boost] [bitstream] Copy stream buffer or pass pointer?
From: Paul Long (plong_at_[hidden])
Date: 2013-07-18 18:30:03

On Thu, 18 Jul 2013 00:27:37 -0700, Dave Abrahams wrote:
> on Wed Jul 17 2013, Daryle Walker <darylew-AT-hotmail.com> wrote:
>
>>> Date: Wed, 17 Jul 2013 22:09:08 -0500
>>> From: plong_at_[hidden]
>>>
>>> For example, the following snippet prints
>>> "hello, goodbye".
>>>
>>> char c[BUFSIZ] = "hello";
>>> istringstream iss(c);
>>> strcpy(c, "goodbye");
>>> cout << iss.str() << ", " << c;
>>>
>>> However, the library I'm working on doesn't copy. Instead, pointers 
>>> are
>>> passed in and out. So, for example, this code prints "goodbye, 
>>> goodbye".
>>>
>>> char c[BUFSIZ] = "hello";
>>> ibitstream ibs(c);
>>> strcpy(c, "goodbye");
>>> cout << ibs.data() << ", " << c;
>>>
>>> Copy or don't copy?
>>
>> I would suggest copying.
>
> But when the source is an rvalue, move instead.  That handles the
> efficiency issues.

I don't understand? Can you elaborate? Wouldn't a move also require 
that bytes get copied? Also how does one write code that is overloaded 
for rvalues vs lvalues?

Paul