Re: qw with anonomous list ref

None is better, because they do different things! qw// is basically a compile-time construct that (as Deparse shows) returns a LIST. \ LIST is a special form of reference-list constrctor and returns a LIST where each element is a reference to the element of the original list:

my @x = \qw(a b c);
print "$_ $$_ \n" for @x;
[download]

[] creates an anonymous ARRAY-ref, which turns out to be a scalar value in the end:

my @x = [qw(a b c)]; #@x has one element
print "$_ @$_\n" for @x;
[download]

So when you evaluate \LIST in scalar context, you get what you alway get when forcing a list to scalar context: the last element:

my $x = \qw(a b c);
print "$x $$x\n";
[download]

HTH

--
http://fruiture.de

Comment on Re: qw with anonomous list ref Select or Download Code

Replies are listed 'Best First'.
Re: Re: qw with anonomous list ref by John M. Dlugosz (Monsignor) on Oct 29, 2002 at 15:14 UTC
I didn't realize that \LIST went "hyper" and applied the ref element-wise. Thanks.	[reply]
Re: Re: qw with anonomous list ref by Jenda (Abbot) on Oct 29, 2002 at 21:15 UTC
Does anyone have any idea what would this be good for? I can't imagine any use for \(list). The only thing that comes to mind is `$ref = \($hashref->{key}->{subkey});` [download] In this case the `$ref = \{$hashref->{key}->{subkey}};` [download] would mean something totaly different ($ref would be a reference to an anonymous hash) and `$ref = \$hashref->{key}->{subkey};` [download] is not very clear. So are there any other uses? Jenda	[reply] [d/l] [select]
Re: Re: Re: qw with anonomous list ref by BrowserUk (Patriarch) on Oct 29, 2002 at 21:57 UTC
I have used it once for setting up an AoA structure. I filled 3 seperate arrays from reading and processing 3 different files and then combined them `my @AoA = \(@a, @b, @c);` [download] Slightly easier than initialising (or pushing) 3 anon arrays and then filling them with `push @{$AoA[n]}, $stuff;` or whatever. Nah! Your thinking of Simon Templar, originally played by Roger Moore and later by Ian Ogilvy	[reply] [d/l] [select]
Re^3: qw with anonomous list ref by Aristotle (Chancellor) on Oct 29, 2002 at 22:58 UTC
Most often I use this to do something to several arrays at once: `my %silly_example; for(\(@couple, @of, @arrays, @here)) { $silly_example{shift @$_}++; splice @$_, 7, 1; push @$_, shift @$_; }` [download] Occasionally it comes it handy for a similar use of map or some such. Makeshifts last the longest.	[reply] [d/l]
\(LIST) useful with DBI bind_columns by blssu (Pilgrim) on Oct 30, 2002 at 12:59 UTC
If you're using DBI, then code like this: `$st->bind_columns(undef, \$a, \$b, \$c)` can be written as `$st->bind_columns(undef, \($a, $b, $c))` That may be slightly easier to maintain. However, two caveats: The \(LIST) form is confusing to many who read it, so make sure you are very consistent. Most code I've seen use bind_columns() is less readable than fetch_hashref(), so if you're thinking of changing your coding style, think about dropping bind_columns() altogether.	[reply] [d/l] [select]