[kw-pm] conditionals and the comma operator
Robert P. J. Day
rpjday at crashcourse.ca
Mon Jan 5 04:41:33 PST 2009
i'm sure i'm about to embarrass myself with how much i've forgotten
my perl, but i'm reading a perl program and, early on, it sets default
command line args thusly:
================================
my ($input,$vm_output,$rfs_output) = @ARGV;
$vm_output = cwd . '/vmlinux',
if (! defined ($vm_output) || $vm_output eq '');
$rfs_output = cwd . '/initramfs.cpio.gz',
if (! defined ($rfs_output) || $rfs_output eq '');
...
================================
i know what that early processing is meant to do -- assign default
values to $vm_output and $rfs_output unless the user has specified
those values on the command line. but how is that being done above?
i vaguely recall that there was a perl idiom that involved the comma
operator to do something like that, but i don't see how that's being
done above. can someone refresh my memory? thanks.
rday
--
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry:
Have classroom, will lecture.
http://crashcourse.ca Waterloo, Ontario, CANADA
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