A twisty little maze of ampersands, all different

[haj]

The following code prints a 0, a 1, a 2, and an empty line. But which is which?

use 5.020;
sub one { 1 }
sub two { 2 }

say one&two     ;
say &one&two    ;
say &one&&&two  ;
say &&&one&&&two;

It is not that difficult to figure out, it was a accidental discovery while messing around with syntax highlighting. For the friends of JAPH, here's one with five consecutive ampersands:

use 5.020;
sub s { say };
$_ = 'Jusst another Perl hacker';
s&s&&&&&s

[kcott]

G'day haj,

++ That's very interesting. Using

perl -MO=Deparse,p -E 'sub one {1} sub two {2} say <ampersand-part>'

I get:

one&two      : say one(&two);
&one&two     : say &one & two();
&one&&&two   : say &one && &two;
&&&one&&&two : &two if say $_ and &one;

Just for completeness, each of those is preceded by:

use feature 'current_sub', 'bitwise', 'evalbytes', 'fc', 'postderef_qq
+', 'say', 'state', 'switch', 'unicode_strings', 'unicode_eval';
sub one {
    1;
}
sub two {
    2;
}

and ends with:

-e syntax OK

And I'm using 5.34.0.