In FAT if you delete item from the directory it is still present but marked as deleted.

So the fact that it is still present does not change the fact that semantically it is deleted.

Further to stevieb's and haukex's comments:   In a file system, if you delete a file and then create another file with the same name, do you get any warning that the old file still, in any sense, "exists", or "masks" anything, or that there is any possible symbol/name collision? The symbol spaces of Perl are not file systems.

c:\@Work\Perl\monks>perl -wMstrict -le
"my $scalar = 42;
 undef $scalar;
 my $scalar;
"
"my" variable $scalar masks earlier declaration in same scope ...
[download]

Of course, this message is only emitted if warnings are enabled, but it highlights the fact that an undef-ed scalar still very much exists. (Same behavior with our package-global scalars.)

I think the critical point that you miss is that undef is a very well-defined value! It is not random, it can be tested, scalars having that value exist in every sense, etc.

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.