How is that execution-order unsafe? ?:'s first operand has to be evaluated before either the second or third.

After writing the above, I checked perlop.pod, and technically you are correct. ?: isn't documented as short-circuiting, so perl potentially could evaluate the 2nd and 3rd operands before testing the first one. However, I believe that it is intended to short-circuit and will submit a patch to the doc.

As an interesting side note, structures with else or elsif are implemented using condexpr (the ?: operator). That is, 

if (foo) { bar } else { baz }

[download]
is identical to 
foo ? do { bar } : do { baz }

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so the short-circuiting of ?: is pretty guaranteed.

In reply to Re^3: Confused by Perl ternary operator by ysth
in thread Confused by Perl ternary operator by newest_newbie

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