[Nms-cgi-devel] Open question on variable/constants

[Olivier D. <dr...@sh...>]

Hi,

I would just like to submit a question to everyone to either answer or
debate.

Would it be a better programming practice to use subroutines instead of
variables as constants? (As my knowledge of Perl is relatively limited,
please let me know if this is not backward compatible to 5.004_04)

Let me explain why I believe that yes is the right answer. I've been
told several times and read it various times as well that a constants is
simply a function that takes no arguments and only returns a value.
Here's an example taken from formmail:

my $emulate_matts_code = 0;
my $secure = 1;
my $mailprog = '/usr/lib/sendmail -oi -t';
my @referers = qw(dave.org.uk 209.207.222.64 localhost);
my @allow_mail_to = qw(yo...@yo... som...@yo... localhost);

This should be enough to illustrate my example. Now this would be
translated into the following format under the premise:

sub EMULATE_MATTS_CODE	{ 0 }
sub SECURE		{ 1 }
sub MAILPROG		{ '/usr/lib/senmail -oi -t' }
sub REFERERS		{ qw(dave.org.uk 209.207.222.64 localhost) }
sub ALLOW_MAIL_TO	{ qw(yo...@yo... som...@yo... localhost) }

(ps, I might be wrong about the behavior of the last two... but you get
my point, at least I hope. I've been successfully writing programs using
this technique)

My main arguments in favor or this:
1. Subroutine values cannot be modified (these are constants right?)
2. Improved code readability ( &CONSTANT instead of $constant or
$CONSTANT) which really distinguishes between code variables and
constants.
3. Seperate configuration (through constants) and algorithms (that use
variables which makes it easier for newbies or people who wish to learn
Perl).

My main arguments against:
1. Most, if not all Perl programs use scalars, arrays and hashes
variables as constants.
2. Might break MWS (although I don't see why if we get the code working
right with it).
3. Extra work (in the case where it's done by me, cannot be argued as
extra work for others :o)

Whaddyatink?
-Olivier


-- 
+----------------------------------------------+
| Olivier Dragon        dr...@sh... |
| Software Engineering II, McMaster University |
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