note Dominus Says [MeowChow]: <blockquote><i> It looks as if any complex sub-expressions /subroutine calls are evaluated in order, and variables/references are evaluated last. </i></blockquote> That's very astute of you. It's not exactly what's going on, but it's very close. For simple variables, Perl pushes what is effectively a reference onto the stack. But for complex ecpressions, Perl must construct the new value and push a reference to that instead. So if <tt>$i = 2</tt>, then <tt>$i</tt> in the list pushes a reference to <tt>$i</tt> itself, but <tt>$i + 0</tt> copies <tt>$i</tt> and pushes a reference to the copy of the 2. If you later change <tt>$i</tt>, the first 2 changes but the second one doesn't.<p> Your original example works the same way.<p> This could be considered a bug. It has come up on p5p before, but I don't remember what the outcome of the discussion was.<p> Contrary to what [id://66885|chromatic said], it is <i>not</i> a precedence issue. Precedence only affects parsing, not execution. 66880 66897