I added a "code ref" test:

sub c3 { print "Evaluating condition 3\n"; /gamma/; }

while (<DATA>) {
    chomp;
    mff(qr/alpha/ => \&s1,
        qr/beta/  => \&s2,
        \&c3      => \&s3,
        qr/omega/         ) or print "*:$_\n";
}
[download]

The output:

*:This is
1:the alpha
1:but not
1:the omega
2:Now the beta
Evaluating condition 3
2:progressing to
Evaluating condition 3
3:the gamma
3:and finally
*:the omega
*:Did this work?
[download]

Which is what I expected.

Apparently, the "fat comma" ( => ) only quotes bare words. chromatic claims the same in the first paragraph of http://www.modernperlbooks.com/mt/2013/04/the-fat-comma-and-clarity.html.

So, => is not imposing string context on \&c3 so that doesn't get stringified.

ah yes right!

The trap was that hash keys are always strings, but while the arguments look like a hash structure they aren't real keys and values.

I remember now that I fell into this trap before...

But still, when passing values which are supposed to be boolean it's safer to negate them.

Cheers Rolf

_{(addicted to the Perl Programming Language and ☆☆☆☆ :)}

Yes, my scalar test didn't work. See node Re^4: Multi-stage flip-flop? ( till() - proof of concept)

But then I changed the test:

while (<DATA>) {
    chomp;
    mff(qr/alpha/ => \&s1,
        qr/beta/  => \&s2,
        \&c3      => \&s3,
        !!c4()            ) or print "*:$_\n";
}
[download]

which imposes scalar context on the call to c4, so it worked correctly:

Evaluating condition 4
*:This is
Evaluating condition 4
1:the alpha
Evaluating condition 4
1:but not
Evaluating condition 4
1:the omega
Evaluating condition 4
2:Now the beta
Evaluating condition 4
Evaluating condition 3
2:progressing to
Evaluating condition 4
Evaluating condition 3
3:the gamma
Evaluating condition 4
3:and finally
Evaluating condition 4
*:the omega
Evaluating condition 4
*:Did this work?
[download]

Clearly should be mentioned in the documentation for any future version of mff.