The classical trick is to use ~~ which is bitwise negation applied twice. It doesn't work for references or anything slightly magical as it numifies or stringifies its operand.

Personally though, I have no problems what so ever with scalar() and the indent of its use can't be any clearer. I advocate for the use of scalar().

Update:
You can also do (my $whatever = ...) but that's also ugly and not a perfect equivalent to scalar(), which I must emphazise is the perfect function for this with no pitfalls. The scalar assignment operator returns the LHS, i.e. e.g. \(my $whatever = ...) references $whatever and not the expression you wanted in scalar context.

Your sub ss ($) { $_[0] } function isn't either a perfect equivalent to scalar() since it returns a copy of the value.

    my $foo;
    print \$foo eq \scalar($foo); # true
    print \$foo eq \ss($foo);     # false
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I can see this as a fun exercise or quiz but I really have to question practicing using anything but scalar() as a general scalar context enforcing operator for anything except obfuscation.

ihb

Read argumentation in its context!