Re: Small question about performance

On Thu, Mar 15, 2012 at 4:54 PM, Nikita Popov <nikita.ppv@googlemail.com> wrote: > On Thu, Mar 15, 2012 at 5:22 PM, Patrick ALLAERT <patrickallaert@php.net> wrote: >> 2012/3/15 Nikita Popov <nikita.ppv@googlemail.com>: >>> If I am understanding the text correctly it is saying that >>>    $f1 = f1(); >>>    $f2 = f2($f1); >>>    $f3 = f3($f2); >>> is using more memory than >>>    $f3 = f3(f2(f1())); >>> >>> For me this doesn't make any sense. In the latter case PHP will also >>> create temporary variables to store the return values. There should be >>> no difference in memory consumption. >> >> It does make sense to me. >> >> In the first case, when calling f3(), $f1 is still referenced. >> In the second case, when calling f3(), the result of f2() is >> referenced, but there is no more active reference to the result of >> f1(). > I don't really know when PHP frees temporary variables, but my guess > was that they are freed when the scope is left. Each variable has a refcount, then that hits 0 it can be freed up. > > If that is not true, then forget whatever I said. > > But if it is true, then there is no inherent difference between the > two version. The only difference is that explicit $variables would > need an entry in the active symbol table, which is pretty much > negligible. > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php >