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Diffstat (limited to 'pod/perltrap.pod')
| -rw-r--r-- | pod/perltrap.pod | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/pod/perltrap.pod b/pod/perltrap.pod index 79e3ae5ca9..dd219c064b 100644 --- a/pod/perltrap.pod +++ b/pod/perltrap.pod @@ -324,6 +324,12 @@ Using local() actually gives a local value to a global variable, which leaves you open to unforeseen side-effects of dynamic scoping. +=item * + +If you localize an exported variable in a module, its exported value will +not change. The local name becomes an alias to a new value but the +external name is still an alias for the original. + =back =head2 Perl4 Traps @@ -486,6 +492,27 @@ works fine, however. =item * +The meaning of foreach has changed slightly when it is iterating over a +list which is not an array. This used to assign the list to a +temporary array, but no longer does so (for efficiency). This means +that you'll now be iterating over the actual values, not over copies of +the values. Modifications to the loop variable can change the original +values. To retain Perl 4 semantics you need to assign your list +explicitly to a temporary array and then iterate over that. For +example, you might need to change + + foreach $var (grep /x/, @list) { ... } + +to + + foreach $var (my @tmp = grep /x/, @list) { ... } + +Otherwise changing C<$var> will clobber the values of @list. (This most often +happens when you use C<$_> for the loop variable, and call subroutines in +the loop that don't properly localize C<$_>.) + +=item * + Some error messages will be different. =item * |