diff options
Diffstat (limited to 'pod/perldiag.pod')
| -rw-r--r-- | pod/perldiag.pod | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/pod/perldiag.pod b/pod/perldiag.pod index 483d164f49..5bf28c8bcc 100644 --- a/pod/perldiag.pod +++ b/pod/perldiag.pod @@ -1517,9 +1517,20 @@ array is empty, just use C<if (@array) { # not empty }> for example. =item defined(%hash) is deprecated -(D deprecated) defined() is not usually useful on hashes because it -checks for an undefined I<scalar> value. If you want to see if the hash -is empty, just use C<if (%hash) { # not empty }> for example. +(D deprecated) C<defined()> is not usually useful on hashes; it merely +checks for non-empty, similar to a hash in boolean context (see +L<perldata>). If a non-empty check is what you want then just use: + + if (%hash) { + # not empty + } + +If you had C<defined(%Foo::Bar::QUUX)> to check whether such a +package variable exists, then it has never actually done that, +but instead creates the hash if necessary (autovivification) +then tests for non-empty. If you really want to check +existence of a package variable then look at the glob slot +with C<defined *Foo::Bar::QUUX{HASH}> (see L<perlref>). =item (?(DEFINE)....) does not allow branches in regex; marked by <-- HERE in m/%s/ |