in reply to Inchworm vs scalar: on boolean false value
There are two things at work here. First, the false value of perl is actually neither strictly '' nor 0, it's kinda both (link to the doc when I find it). As demonstrated by
The warning about the non numeric argument happens only once, because !1 is treated as a number in arithmetic context. But printing !1 doesn't show anything because false is the empty string in string context.perl -E "use strict; use warnings; say( '' + 1 ); say( !1 + 1 ); say ! +1; say '!1 is defined' if defined !1" Argument "" isn't numeric in addition (+) at -e line 1. 1 1 !1 is defined
~ however only works in two ways: bitwise not on a number, or bitwise not on a binary string. And the output will be of the same type. This means that ~~ is only equivalent to scalar when the operand is a number or a string, but it will force another type (probably string) on any other value (an object, a reference...).
Edit: one place where the special value of perl's false is mentioned: Relational Operators.
Also, ~~ is not equivalent to scalar for some big numbers and negative numbers:
So it's better not to use it outside of obfuscated code.DB<1> say ~~ (-1) 18446744073709551615
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