There is also something to be said for writing clear and obvious code, even if it does
cost a couple of CPU cycles of which there are about 2.5 billion available every second.
I prefer this version :
my $args = $r->args;
if (defined($args) && ($args eq 'last')) {
...
}
unless $args is used exclusively inside the if {} block (*).
Clear, no side-effects, no hidden meaning behind the "if ($args)", no double dereferencing
overhead - assuming perl doesn't optimise this itself - , no worries about operator
precedence etc.
Syntactic sugar and perl virtuosity are nice if they are for one's self-satisfaction,
hubris and laziness, but if some junior has to handle this code after you lose interest,
it's better to be plain and obvious.
(*) in which case I might just about forgive you for writing
if (defined(my $args = $r->args) && ($args eq 'last')) {
, although that would probably force the junior to consult the (otherwise excellent and
humorous) perl documentation to verify the scope of $args.
Mark Hedges wrote:
Nope Joshua you're right, I missed that.
defined() is faster than the logical check because the logical check checks
defined, then checks if empty string, then checks if numerically 0, except if
it is 0E0 (zero but true). One operation versus the same operation plus three
more; the one by itself is certainly less computation.
However I'm not sure about the last one. That is a cool idea. We'd have to
benchmark it. :-)
Also is '&&' faster than 'and'?
Mark
From: sergiy.borod...@gmail.com [mailto:sergiy.borod...@gmail.com] On Behalf Of
Sergiy Borodych
Sent: Thursday, June 26, 2014 2:14 AM
To: Joshua Narins
Cc: Mark Hedges; modperl@perl.apache.org
Subject: Re: bug in trunk in Apache::Reload test
Hello,
another question:
why not just
my $args = $r->args;
if ( $args and $args eq 'last' ) {
(without defined)
or even
if ( my $args = $r->args and $args eq 'last' ) {
:)
2014-06-26 10:52 GMT+03:00 Joshua Narins <j...@mobehr.net>:
On Mon, Jun 23, 2014 at 06:21:37PM +0000, Mark Hedges wrote:
Perl 5.20.0, Apache 2.2.27, APR 1.5.1, APR-util 1.5.3, mod_perl trunk.
2014-06-23 11:16:32 Mon $ svn diff t/lib/Apache2/TestReload.pm
Index: t/lib/Apache2/TestReload.pm
===================================================================
--- t/lib/Apache2/TestReload.pm (revision 1604706)
+++ t/lib/Apache2/TestReload.pm (working copy)
@@ -15,7 +15,8 @@
sub handler {
my $r = shift;
$pass++;
- if ($r->args eq 'last') {
+ my $args = $r->args;
+ if (defined $args && $r->args eq 'last') {
Apache2::Reload->unregister_module($package);
ModPerl::Util::unload_package($package);
$pass = 0;
Why not just
my $args = $r->args;
if (defined $args and $args eq 'last') {
I guess repeat calls to $r->args have virtually no cost?
