perlmeditation
punkish
<b>Update:</b> <i>Several rules now modified to reflect the feedback from wise monks (credited, hopefully, correctly, below the respective rule).</i>
<hr>
Larry's philosophy that different things should look different is one of the most beautiful and powerful strengths of Perl. We are immediately guided by the $, @, and % as to the nature of the variable (cr: [TimToady]).
<p>
However, for my purpose, it can go even further. With that in mind, I came up with the following <strike>9</strike> 10 rules while coding a reasonably complicated project.
<p>
Coding strategies are personal by nature, but much can be learned from those who are wiser. Hence, I put forth my rules to get comments from the more learned monks than I --
<p>
<code>
# 0. Just-in-time variable declaration and initialization.
</code>
(cr: [merlyn])
<code>
# 1. Variables in consistent case (all lower or all upper)
# 2. Each dictionary word in the variable name separated
# by underscore, unless accepted as one word by usage as
# in 'username' or 'logout'
# 3. Package variables in all caps, used for things like
# config values
use vars qw(
$FOO
$BAR
$BAZ
$FOO_BAR
);
</code>
<strike>
<pre>
# 4. Lexicals in all lower case
my ($foo, $bar, $baz, @foo_bar);
</pre>
</strike>
<code>
# 4. Global lexicals in all lower case, and
# prefixed with some text to mark them as such.
# For example...
my ($glob_foo, $glob_bar, $glob_baz, @glob_foo_bar);
</code>
<strike>
<pre>
# 5. Variables local to a subroutine prefixed by some
# consistent prefix such as 'this_' or 'local_'. This way
# there never will be any confusion as to whether a
# given variable sprang into life in the subroutine
# of if it exists in the outside world and might possibly
# get clobbered locally.
sub foo {
my ($this_bar) = @_;
for (@$this_bar) {
print "yay" if ($_ eq $FOO);
}
return $this_bar;
}
</pre>
</strike>
<code>
# 5. Local lexicals on all lowercase
sub foo {
my ($bar) = @_;
for (@$bar) {
print "yay" if ($_ eq $FOO);
}
return $bar;
}
</code>
#4 and #5 above flipped (cr: [Forsaken])</br>
<code>
# 5.5. Use prefixes to scope other logically different
# vars. For example, 'cgi_' to prefix vars holding
# params delivered via the cgi
my $cgi_foo = $cgi->param('foo');
my $cgi_bar = $cgi->param('bar');
# 6. Refs prefixed with the appropriate identifier. I wish
# Perl would extend the "different things look different"
# to enable easy identification of the kind of data
# structure a ref refers to.
my $aref_bar = foo(\@foo_bar);
# 7. Rules 1-5 apply to rule 6 as well... so, an array ref
# inside a sub would be $this_aref_bar, etc.
</code>
<strike>
<pre>
# 8. Subroutines named in camelCase with the first letter
# lower case
sub normalizeThisMonkeyBoy {
}
</pre>
</strike>
<code>
# 8. modified: I like camelCase, however, the real purpose
# here is to visually distinguish a sub from a var. Choose
# your method
# 9. Subroutines not exported from a package prefixed with
# an underscore
package Foo;
@EXPORT = qw(
startProgram
watchOut
goHome
);
sub startProgram {
_wakeUp();
}
sub watchOut {
_keepEyeOpen();
}
sub goHome {
_nightyNight();
}
sub _wakeUp {}
sub _keepEyeOpen {}
sub _nightyNight {}
# 9.5. Never export anything by default.
@EXPORT_OK
</code>
(cr: [TilRMan])<br>
<code>
# 10. Always pass named vars to subs
doThis('with' => $that, 'and' = $something_else);
</code>
<div class="pmsig"><div class="pmsig-231169">
--
<br><br><i>
when small people start casting long shadows, it is time to go to bed</i>
</div></div>
<p><small>Janitored by [holli] - moved to [Meditations]</small></p>