* I updated the answer to note that we've fixed this bug. I kept
the old answer around although I added example output to clarify
the symptoms.
* This might be a candidate for removal.
Index: perlfaq7.pod
===================================================================
RCS file: /cvs/public/perlfaq/perlfaq7.pod,v
retrieving revision 1.25
diff -u -d -r1.25 perlfaq7.pod
--- perlfaq7.pod 8 Aug 2005 02:38:25 -0000 1.25
+++ perlfaq7.pod 10 Oct 2005 18:58:04 -0000
@@ -271,24 +271,40 @@
=head2 What is variable suicide and how can I prevent it?
-Variable suicide is when you (temporarily or permanently) lose the
-value of a variable. It is caused by scoping through my() and local()
-interacting with either closures or aliased foreach() iterator
-variables and subroutine arguments. It used to be easy to
-inadvertently lose a variable's value this way, but now it's much
-harder. Take this code:
+This problem was fixed in perl 5.004_05, so preventing it means
upgrading
+your version of perl. ;)
- my $f = "foo";
+Variable suicide is when you (temporarily or permanently) lose the
value
+of a variable. It is caused by scoping through my() and local()
+interacting with either closures or aliased foreach() iterator
variables
+and subroutine arguments. It used to be easy to inadvertently lose a
+variable's value this way, but now it's much harder. Take this code:
+
+ my $f = 'foo';
sub T {
- while ($i++ < 3) { my $f = $f; $f .= "bar"; print $f, "\n" }
+ while ($i++ < 3) { my $f = $f; $f .= $i; print $f, "\n" }
}
T;
print "Finally $f\n";
+If you are experiencing variable suicide, that C<my $f> in the
subroutine
+doesn't pick up a fresh copy of the C<$f> whose value is <foo>. The
output
+shows that inside the subroutine the value of C<$f> leaks through when
it
+shouldn't, as in this output:
+
+ foobar
+ foobarbar
+ foobarbarbar
+ Finally foo
+
The $f that has "bar" added to it three times should be a new C<$f>
-(C<my $f> should create a new local variable each time through the
loop).
-It isn't, however. This was a bug, now fixed in the latest releases
-(tested against 5.004_05, 5.005_03, and 5.005_56).
+C<my $f> should create a new lexical variable each time through the
loop.
+The expected output is:
+
+ foobar
+ foobar
+ foobar
+ Finally foo
=head2 How can I pass/return a {Function, FileHandle, Array, Hash,
Method, Regex}?
--
brian d foy, [EMAIL PROTECTED]
