perl qstn...

[Alejandro Imass]

On Sun, Apr 4, 2010 at 2:14 PM, Polytropon <freebsd at edvax.de> wrote:
> On Sun, 4 Apr 2010 10:33:53 -0600, Chad Perrin <perrin at apotheon.com> wrote:
>> On Sun, Apr 04, 2010 at 12:45:30PM -0400, Alejandro Imass wrote:
>> > did you mean unless? ;-)
>>
>> I find "if" to be clearer than "unless" when there's an "else", so
>> instead of making that "if" into an "unless", I'd just swap the
>> conditional actions.
>
> A quite language-independent technical sidenote :-) ...
>

<grin>

> If your if() conditional is to test an exception, something
> that you usually DON'T want to happen - i. e. missing command
> line parameters - you can use the ! negation operator to
> indicate this in the if() argument.
>

_precisely_ what unless is for. it's just a funny way of writing
if(!... or should I say if(! is a funny way to write unless ;-)

But honestly pun aside unless(){} is far more readable than if(!){}
and _especially_ if you are programming in an exception manner as you
correctly point out. Every language should have an unless construct.

[...]
> And you could even force perl to exit with an exit code != 0
> to indicate that something happened (e. g. program wasn't run
> successfully).
>

a good practice in any language...

> Now, as the "don't want case" has been considered, you can
> easily continue with your program, no need to put it into
> an else { } branch.
>

ahh! the clarity of unless

>
>
>
> PS. I'm not familiar with perl enough to be sure that the !
>    operator can be used at @ARGV to make sure it's > 0,

In "scalar context" will automagically return the number of elements

perldoc perlintro (section Perl variable types)

>    and how or if to use exit() to set the return code.

die "Bailing cause you forgot the filename" unless @ARGV

Yes, that _is_ actual code :) Will not only die with a pretty message
on STDERR but will return the value of $! (errno) as exit value. (no
need to make up exit codes) Good thing we are on a FBSD list, because
I can't see the sense of programming in a non-nix environment ;-)

>    I hardly can read perl at all, so the essence of my
>    examples is of a rather generic nature. :-)

Look mommi! Reading Perl is just like reading plain english! (or in
Nigerian spam for that matter
http://search.cpan.org/~jwalt/Acme-Lingua-NIGERIAN-1.0.0/NIGERIAN.pm)

Cheers,
Alejandro Imass

>
> --
> Polytropon
> Magdeburg, Germany
> Happy FreeBSD user since 4.0
> Andra moi ennepe, Mousa, ...
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