First of all, push is not a subroutine. I'll concentrate on your second example, sub name (\@@).

While it could be a matter of interpretation in general, it's unequivocal in this case because we're talking about the value of $_[0]. The \@ prototype causes a reference to the array to be passed to the sub, not an array. $_[0] contains a reference, not an array. Printing \$_[0] would print a reference to a reference to an array, not a reference to an array.

In reply to Re^3: Reference of constants and literals by ikegami
in thread Reference of constants and literals by LanX

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