On 06/14/2018 01:13 PM, Trey Harris wrote:
Just a small stylistic thing to mention:
On Thu, Jun 14, 2018 at 1:59 AM Todd Chester <toddandma...@zoho.com
<mailto:toddandma...@zoho.com>> wrote:
p6
if not $dir.IO.d.bool {}
for slice "\n", $WebStr -> $Line { }
and on and on and so forth. I know a lot of them by heart now.
By |.bool|, I assume you meant |.Bool|, but in any case, it isn’t
necessary since the context of a |not| forces it to be boolean.
Indeed!
Exists (directory):
DIRPATH.IO.d.Bool;
if not $WorkingDir.IO.d.Bool { mkdir $WorkingDir, 0o766; }
If you want the opposite—a boolean without the sense-negation, you can
use |so|, but in the context of an |if|, it should rarely, if ever, be
necessary.
In the same way that |so| is used to explicitly truthify, unary |+| is
used to explicitly numify.
E.g., once you know that an |IntStr|
<https://docs.perl6.org/type/IntStr> dual value gives a result
reminiscent of Perl 5’s string numbers (except that without going to
crazy lengths, you can easily supply exactly the number and string you
want):
|my $x = IntStr.new(42, "The Answer"); my $y = IntStr.new(0, "Nothing");
for ($x, $y) -> $z { printf "\$z: '%s', so \$z: '%s', +\$z: '%s'\n", $z,
so $z, +$z; say " Double it: ", $z * 2; say " or 'double' it: ", $z x 2; } |
gives results:
|$z: 'The Answer', so $z: 'True', +$z: '42' Double it: 84 or 'double' it:
The AnswerThe Answer $z: 'Nothing', so $z: 'False', +$z: '0' Double it:
0 or 'double' it: NothingNothing |
In case you’re wondering, you’ll usually have no reason to explicitly
construct a dual value like that; you generally get a NumStr or its
counterparts like IntStr when reading input or expecting command-line
arguments.
(Also note that the stringification equivalent to |so| and unary |+| is
|~|, but it wasn’t necessary above since the |%s| template to |sprintf|
forces stringification. Also note that using s/printf at all is not
encouraged—but it was useful above, just to make things explicit.)
Thank you! Wonderful exposition! I am going to write it down
for later use.
I use "if not" a lot because it is human readable for
me and assists in maintaining the code.
