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Postings from April 2010
* Tom Christiansen <tchrist@perl.com> [2010-04-04 00:40]:
> Yes, it's somewhat clearer to write:
>
> for my $tick (reverse 1 .. 10) { ... }
>
> for our $Arg (@ARGV) { ... }
>
> And I do admittedly do this in my own code, except perhaps for
> implicit $_.
As do I.
> However, I truly do not believe cluttering every example with
> a declaration for each variable used makes it clearer or
> better.
I never talked about that. My point was purely about `foreach`;
and I am glad to hear we essentially agree on that issue.
> An example that demonstrates, say, the abs($x) function, should
> be able to be written
>
> $x >= 0 ? $x : -$x
>
> without any needlessly distracting declarations.
>
> Eh?
Sure, one can’t declare `$x` en passant there.
> ########################
>
> Similarly,
>
> dbmopen(%HIST,'/usr/lib/news/history',0666);
> while (($key,$val) = each %HIST) {
> print $key, ' = ', unpack('L',$val), "\n";
> }
> dbmclose(%HIST);
>
> is not improved by being written
>
> dbmopen(my %HIST,'/usr/lib/news/history',0666);
> while (my($key,$val) = each %HIST) {
> print $key, ' = ', unpack('L',$val), "\n";
> }
> dbmclose(%HIST);
Yes it is. Modulo coding style, that is certainly how I would
write it if I were doing this in real code. Funnily enough what
I wrote about `foreach` applies here: `%HIST` is shadowed for the
duration of the tie, so the behaviour with a predeclared variable
is unlikely to be useful. Likewise, I am extremely unlikely to
ever write that `while` loop using previously declared variables
(unless it’s `($a, $b)` because I’m writing a one-liner).
> Here's an example of gratuitous my() confusing matters:
>
> my @abbr = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
> print "$abbr[$mon] $mday";
> # $mon=9, $mday=18 gives "Oct 18"
>
> I might have written that as
>
> @abbr = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
> print "$abbr[$mon] $mday\n"; # use old $mon, $mday vals
> # $mon=9, $mday=18 gives "Oct 18"
I think it is implied there that the variables are those
introduced in the previous code example. A `my` in front
of that one would help, admittedly.
--
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&Just->another->Perl->hack;
#Aristotle Pagaltzis // <http://plasmasturm.org/>
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