[vdr] Re: cString operator= with same buffer

Mws mws at twisted-brains.org
Sun Nov 20 22:16:58 CET 2005


On Sunday 20 November 2005 22:07, Jon Burgess wrote:
> Sascha Volkenandt wrote:
> > Would you mind to explain how you get two strings pointing to the same buffer 
> > after the copy ctor is safe (makes a copy instead of taking the buffer)? IMHO 
> > the copy ctor already takes care that doesn't happen (except if you hand over 
> > the same buffer to two cStrings with TakePointer = true, which is IMHO not 
> > intended).
> 
> As you say, all normal usage should be between 2 different buffers. It 
> doesn't seem legal to me that 2 cStings would share the same buffer. 
> This would always cause things to blow up when the destructors are called.
> 
> The only way that I can come up with is to assign a cString to itself 
> (as per my example main.c elsewhere in this thread). I imagine this 
> could happen legally under some limited circumstances.
> 
> I don't know the details of the scenario seen by Holger.
> 
> 	Jon
hi, 
sometimes this is done with a sense.

if you have a look at the standard template library,
you'll find out that the strings - exactly the content - 
is shared by refcounting and a copy is just done, if it is needed.

i had a short look at the tools.c/h files and closed them fast again.
imho mixing up c & c++ permanently is not a good style at all.

have a look at std::basic_string.
it is working with copy_on_write.

just my 2ct

marcel



More information about the vdr mailing list