I finally understand the tao of slices. After reading through Effective Perl Programming this weekend, I have figured out a problem that was holding me back. While I am sure that the majority of you have had this epiphany long ago, I feel the need to beat my chest and howl about it...

It began, while I was trying to read in, modify and write out shadow file entries: 

open(TEMPFILE, ">${TempPath}/temp_shad") || die;
open(SHADFILE, "${TempPath}/$passwdfile") || die;
while (<SHADFILE>) {
    chomp;
    (@entry) = split(/:/,$_);
        $newentry = join(":", @entry);
        print TEMPFILE "$newentry\n";

[download]

This didn't work, because, as you know (if you are a *nix SA), the shadow file looks like so: foo:asDflkj123./d:6445::::::

So when I wrote it back out,this is what I got:

foo:asDflkj123./d:6445

[download]

In comes the concept of slicing <*trumpet sounds*>. Thru the slice, I was able to define those empty fields, while not having to worry about assigning bogus values that I would have to delete. Also, I didn't have to deal w/ trying to assign each field to an individually defined variable and the long lines of code that followed: 

($user,$passwd,$mod,$f1,$f2,$f3,$f4,$f5) = split(/:/,$_);
$newentry = "$user" . ":" . "$passwd" . ":" . "$mod" . ":" . "$f1" . "
+:" . "$f2" . ":" . "$f3" . ":" . "$f4" . ":" . "$f5)\n";

[download]
The above code works, but geez, I don't want to have to type all of that each time I need to modify the shadow file.

That code became this:

        (@entry[0..8]) = split(/:/,$_);
        $newentry = join(":", @entry[0..8]);

[download]
In short, it made a potentially arduous task, very simple and easier to read.

Now, back to the regularly scheduled program...

Enlightened,

bb

update: fixed # of colons in shadow file entry, thanks davorg

In reply to I am now slice-aware by birdbrane

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