Re: [Libreoffice] [PATCH] Accelerate perl installer: optimize installer::scriptitems::optimize_list().

(apologies for breaking the thread; I only just subscribed)

I offered an opinion on this excellent little patch to Caolán on IRC,
basically that I thought the last foreach()/chop combo would be better
written as a join. A minor nit, but probably not with much speed
benefit.

The more perlish version of optimize_list() would probably look more
like this:
        
        sub optimize_list {
                my ($longlist) = @_;
                
                $longlist =~ s/^\s+//;
                $longlist =~ s/\s+$//;
                
                my %seen;
                my @shortlist = sort grep {
                        ! $seen{$_}++;
                } split(/\s*,\s*/, $longlist);
                
                return join(',', @shortlist);
        }

grep is quasi-functional, but the nicest way of operating on arrays of
things rather than doing string ops.

In general, doing a lot of text operations - like running regexes over a
string that you later split anyway - will tend to slow things down a
bit, although I would doubt any difference between my version and
Jordan's would be amazingly significant unless the lists are quite long.

I haven't looked at a huge amount of the installer, but it might be that
internally using strings less and data structures more could be used to
speed it up a fair bit: having a look around, there's a long of string
building and stuff going on and it's not really clear that's usually a
win.

It might be worth dumping out some of the main datastructures from that
cruft to actually see what's going on...

Ta

Alex.


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