I was reading about the -s switch in the Camel book and noticed something that I can't figure out. The following script is taken directly from the book (p. 499, 3rd ed.): 
#!/usr/bin/perl -s
if ($foo eq 'bar'){ print "true\n" }

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When invoked like so: 
mojodaddy@muchomojo:~$ perl foo_eq_bar.pl -foo=bar

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it should print "true", or at least my reading of the text suggests that it should, but it prints nothing. This script: 
#!/usr/bin/perl -s
if ($foo){ print "true\n" }

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prints "true" with either a -foo or a -foo=bar switch. And finally this script: 
#!/usr/bin/perl -s
if ($foo eq 'bar'){ print "true\n" }
if ($foo){ print "woo\n" }
print "woo-hoo\n" if $foo eq 'bar';
print "woopty-doo\n" if $foo;

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will only ever print "woo" and "woopty-doo" whether it is invoked with a -foo or -foo=bar switch. Can anyone explain what's going on? Have I gone through the looking glass? Or do I just need a new pair of glasses?

In reply to unexpected results using -s switch by mojodaddy

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