diff options
| -rw-r--r-- | pod/perlfunc.pod | 39 |
1 files changed, 24 insertions, 15 deletions
diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index 14582f5a9c..18787fe0fd 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -1176,21 +1176,25 @@ See also L</undef>, L</exists>, L</ref>. =item delete EXPR X<delete> -Given an expression that specifies an element or slice of an aggregate (a -hash or an array), deletes the specified elements from that aggregate so -that exists() on that element no longer returns true. Setting an aggregate -element to the undefined value does not remove its key, but deleting it -does; see L</exists>. +Given an expression that specifies an element or slice of a hash, C<delete> +deletes the specified elements from that hash so that exists() on that element +no longer returns true. Setting a hash element to the undefined value does +not remove its key, but deleting it does; see L</exists>. -Returns the value or values deleted in list context, or the last such +It returns the value or values deleted in list context, or the last such element in scalar context. The return list's length always matches that of -the argument list: deleting non-existent elements returns the undefined -value in their corresponding positions. +the argument list: deleting non-existent elements returns the undefined value +in their corresponding positions. -Deleting array elements never changes indices of existing values; use -shift() or splice() for that. However, if all deleted elements fall at -the end of an array, the array's size shrinks to the position of the -highest element that still tests true for exists(), or to 0 if none do. +delete() may also be used on arrays and array slices, but its behavior is less +straightforward. Although exists() will return false for deleted entries, +deleting array elements never changes indices of existing values; use shift() +or splice() for that. However, if all deleted elements fall at the end of an +array, the array's size shrinks to the position of the highest element that +still tests true for exists(), or to 0 if none do. + +B<Be aware> that calling delete on array values is deprecated and likely to +be removed in a future version of Perl. Deleting from C<%ENV> modifies the environment. Deleting from a hash tied to a DBM file deletes the entry from the DBM file. Deleting from a C<tied> hash @@ -1740,14 +1744,19 @@ C<DESTROY> methods on your objects. =item exists EXPR X<exists> X<autovivification> -Given an expression that specifies an element of a hash or array, -returns true if the specified element in that aggregate has ever -been initialized, even if the corresponding value is undefined. +Given an expression that specifies an element of a hash, returns true if the +specified element in the hash has ever been initialized, even if the +corresponding value is undefined. print "Exists\n" if exists $hash{$key}; print "Defined\n" if defined $hash{$key}; print "True\n" if $hash{$key}; +exists may also be called on array elements, but its behavior is much less +obvious, and is strongly tied to the use of L</delete> on arrays. B<Be aware> +that calling exists on array values is deprecated and likely to be removed in +a future version of Perl. + print "Exists\n" if exists $array[$index]; print "Defined\n" if defined $array[$index]; print "True\n" if $array[$index]; |