I won't get into the train of thought that led to the following thought experiment: 

$foo = "NARGLE";
print ref($foo), "\n";
defined(ref($foo)) ? print "Y\n" : print "N\n";
ref($foo) == undef() ? print "Y\n" : print "N\n";

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The print ref() obviously prints nothing but a newline. However, I was quite surprised when the two trinary statements both printed "Y". I went back to the documentation and looked up both defined() and undef(). Defined "Returns a boolean value telling whether EXPR has a value other than the undefined value 'undef'...". Looking over at the undef docs, it "always returns the undefined value". How is it possible for ref($foo) to be both defined and == undef?

~Cybercosis

nemo accipere quod non merere

In reply to Undefined undef oddness by Cybercosis

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