Re: Ternary vs. Sort vs. Max

[Athanasius]

Hello QM,

Another — possibly heretical? — option is to make max an inline function using a module such as macro:

#! perl
use strict;
use warnings;
use macro max => sub { $_[0] > $_[1] ? $_[0] : $_[1]; };

my $x = $ARGV[0];
my $y = $ARGV[1];
my $m = max($x, $y);

print "max is $m\n";

Output:

 0:05 >perl 1334_Med.pl 17 12
max is 17

 0:05 >perl -MO=Deparse 1334_Med.pl
Compiling 1334_Med.pl by macro::compiler/0.06 ...
sub Digest::base::new;
sub Digest::base::clone;
sub Digest::base::add;
sub Digest::base::digest;
use macro ('max', sub {
    use warnings;
    use strict;
    $_[0] > $_[1] ? $_[0] : $_[1];
}
);
use warnings;
use strict;
my $x = $ARGV[0];
my $y = $ARGV[1];
my $m = $x > $y ? $x : $y;
print "max is $m\n";
1334_Med.pl syntax OK

 0:05 >

Hope that helps,

[QM]

Hi Athanasius,

The macro is indeed interesting, as I've not delved in there before.

However, that may suffer from techical debt. If I define a max macro that only handles 2 values, I (or my replacement) may call it later and give it 3 values, and only get the max of the first 2. Still, some careful coding (probably duplicating List::Util's max) could ensue.

Edited to add:

Also, it seems the macro syntax uses significant whitespace, which bugs me.

Edited to add (2):

The macro doc page has this:

use macro add => sub{ $_[0] + $_[1] };
          say => sub{ print @_, "\n"};
say(add(1, 3)); # it's replaced into 'print do{ (1) + (3) }, "\n";'

which I'm assuming uses significant whitespace to figure out that say is a macro. (Or there's a typo semicolon on the first line.)

[Athanasius]

It’s just a typo:

19:13 >perl pod.pl
Useless use of a constant ("say") in void context at pod.pl line 6.
Useless use of single ref constructor in void context at pod.pl line 6
+.
Undefined subroutine &main::say called at pod.pl line 7.

19:39 >

Whereas with a comma instead of the semicolon:

19:39 >perl pod.pl
4

19:41 >perl -MO=Deparse pod.pl
Compiling pod.pl by macro::compiler/0.06 ...
sub Digest::base::clone;
sub Digest::base::new;
sub Digest::base::digest;
sub Digest::base::add;
use macro ('add', sub {
    use warnings;
    use strict;
    $_[0] + $_[1];
}
, 'say', sub {
    use warnings;
    use strict;
    print @_, "\n";
}
);
use warnings;
use strict;
print 4, "\n";
pod.pl syntax OK

19:41 >

Hope that helps,

[QM]

I raised ticket 106366 for that.