php - Why does empty expect T_PAAMAYIM_NEKUDOTAYIM when a non-variable is given? -

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<?php define('foo', 'bar');  if (empty(foo)) {   echo 'qux'; }

http://codepad.org/g1tsk1c6
parse error: syntax error, unexpected ')', expecting t_paamayim_nekudotayim on line 4

i know empty() allows variables passed argument, why expect t_paamayim_nekudotayim (i.e. ::) when give constant?

the next logical thing parser wants :: because foo not variable.

if (empty(foo::$bar)) { }

is thing, works when empty() not passed variable. example evaluated empty(bar) parser assumes bar class name , expects static member variable.


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