G'day ns550,

If you attempt to use telldir on an invalid directory handle, you'll get a "telldir() attempted on invalid dirhandle" warning (see perldiag). You can promote that warning to an error with FATAL (see the warnings pragma). That error can now be captured and tested.

I created some test files: 

$ ls -al pm_1208018_test_dir*
pm_1208018_test_dir:
total 0
drwxr-xr-x  3 ken staff 102 Jan 30 07:08 .
drwxr-xr-x 20 ken staff 680 Jan 30 07:43 ..
-rw-r--r--  1 ken staff   0 Jan 30 07:08 pm_1208018_test_file

pm_1208018_test_dir_closed:
total 0
drwxr-xr-x  2 ken staff  68 Jan 30 07:40 .
drwxr-xr-x 20 ken staff 680 Jan 30 07:43 ..

pm_1208018_test_dir_empty:
total 0
drwxr-xr-x  2 ken staff  68 Jan 30 07:29 .
drwxr-xr-x 20 ken staff 680 Jan 30 07:43 ..

[download]

I used a standard alias of mine: 

$ alias perle
alias perle='perl -Mstrict -Mwarnings -Mautodie=:all -E'

[download]

I started with a simple, one-liner test. I then added more and more tests: the result wrapped around four lines. Here it is; expanded for ease of viewing. I've also annotated the output in situ. 

$ perle '
    open my $fh, "<", "pm_1208018_test_dir/pm_1208018_test_file";
    opendir(my $dh, "pm_1208018_test_dir");
    opendir(my $eh, "pm_1208018_test_dir_empty");
    opendir(my $ch, "pm_1208018_test_dir_closed");
    closedir $ch;
    my $nh = "42";
    my $uh;
    my %h = (fh => $fh, dh => $dh, nh => $nh, eh => $eh, uh => $uh, ch
+ => $ch);
    for (keys %h) {
        use warnings FATAL => "io";
        eval {
            my $x = telldir $h{$_}; say "$_ is a dirhandle"; 1
        } or say "$_ is not a dirhandle" 
    }
'
fh is not a dirhandle   # fh = filehandle
nh is not a dirhandle   # nh = not a handle (just the number 42)
eh is a dirhandle       # eh = dirhandle to "pm_1208018_test_dir_empty
+"
dh is a dirhandle       # dh = dirhandle to "pm_1208018_test_dir"
ch is not a dirhandle   # ch = closed handle
uh is not a dirhandle   # uh = undefined handle (declared but uninitia
+lised)

[download]

[Note that "pm_1208018_test_dir_empty" isn't technically empty. On *nix machines it shows the "." and ".." entries. I'm not sure how that works on MSWin. I've left it in as a potential edge case.]

— Ken

In reply to Re: Testing for a directory handle by kcott
in thread Testing for a directory handle by ns550

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.