Parameter-driven confusion

use strict;
use warnings;
mysub(74.117.115.116);
mysub(32.97.110.111);
mysub(116.104.101.114);
mysub(32.69.120.99);
mysub(101.108.32.104);
mysub(97.99.107.101);
mysub(114.46.32.8);

sub mysub {
     print $_[0];
}
[download]

I'm posting this as an obfu, but it might well be a SOPW. I ran into it the hard way. My test was passing an IP address - 8.8.8.8 - to a sub in the intended module. The test was failing. When I looked at the value of the param in the sub with Data::Dumper, I got 8.8.8.8, but when I printed the param, nothing appeared. I was wasting time looking at my sub when I should have been looking at the test. I had left out the quotes around the IP address.

I know what my code is doing. What I don't know is why. This construct certainly doesn't DWIM and I can't see why it should be what anyone else would mean. Is there a sensible explanation? And let me add my usual question - is this documented anywhere?

Regards,

John Davies

Comment on Parameter-driven confusion Download Code

Replies are listed 'Best First'.
Re: Parameter-driven confusion by ikegami (Patriarch) on Dec 21, 2019 at 14:12 UTC
See "Version Strings" in perldata.	[reply]
Re: Parameter-driven confusion by shmem (Chancellor) on Dec 22, 2019 at 00:25 UTC
What Ikegami says. And there's the "%v" template (vector flag) for sprintf. So, since this is in obfuscation, here's a golfed cidr calculator: #!/usr/bin/perl # file cidr.pl $m=pack B32,pop=~'/'x$';printf"$` network %vd broadcast %vd netmask %v +d\n",($z=eval$`)&$m,$z\|~$m,$m [download] Note the eval$` bit, which is essentially what happens in your code. Usage example: `shmem [qwurx] ~ > cidr.pl 172.16.242.150/27 172.16.242.150 network 172.16.242.128 broadcast 172.16.242.159 netmask + 255.255.255.224` [download] This cidr appeared one long gone day on IRC in the perlgolf channel iirc. I guess it is off the keyboard of tybalt89, but I might be wrong. perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'	[reply] [d/l] [select]


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