From: Mathieu Bouchard <matju@...>
Date: 2005-09-16T04:33:25+09:00
Subject: Re: array sharing

On Fri, 16 Sep 2005, mathew wrote:

> You can use realloc to make an existing allocated chunk of memory larger, but
> it always extends rightwards.

Most of the time realloc will fail to extend and instead will 
malloc/memcpy/free the stuff for you. This is because Ruby does a lot of 
dynamic allocation and so it's very easy to have an extra malloc done in 
between a malloc and the realloc of it, and very often the extra malloc 
blocks the extensibility of it. It's memory fragmentation at work. This is 
also why it's better to use the exponential reallocation technique that 
Perl/Ruby/Python are using, because you can't expect to get O(1) realloc 
on average.

realloc is enough of a failure that C++ doesn't bother providing an
equivalent to it in the same way that the new/new[]/delete/delete[]
operators are in C++.

____________________________________________________________________
Mathieu Bouchard - t�l:+1.514.383.3801 - http://artengine.ca/matju
Freelance Digital Arts Engineer, Montr�al QC Canada