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corpus/perlfunc.pod  view on Meta::CPAN

=item shift EXPR

=item shift

Shifts the first value of the array off and returns it, shortening the
array by 1 and moving everything down.  If there are no elements in the
array, returns the undefined value.  If ARRAY is omitted, shifts the
C<@_> array within the lexical scope of subroutines and formats, and the
C<@ARGV> array outside a subroutine and also within the lexical scopes
established by the C<eval STRING>, C<BEGIN {}>, C<INIT {}>, C<CHECK {}>,
C<UNITCHECK {}>, and C<END {}> constructs.

Starting with Perl 5.14, C<shift> can take a scalar EXPR, which must hold a
reference to an unblessed array.  The argument will be dereferenced
automatically.  This aspect of C<shift> is considered highly experimental.
The exact behaviour may change in a future version of Perl.

See also C<unshift>, C<push>, and C<pop>.  C<shift> and C<unshift> do the
same thing to the left end of an array that C<pop> and C<push> do to the
right end.

corpus/perlfunc.pod  view on Meta::CPAN

Returns true if the context of the currently executing subroutine or
C<eval> is looking for a list value.  Returns false if the context is
looking for a scalar.  Returns the undefined value if the context is
looking for no value (void context).

    return unless defined wantarray; # don't bother doing more
    my @a = complex_calculation();
    return wantarray ? @a : "@a";

C<wantarray()>'s result is unspecified in the top level of a file,
in a C<BEGIN>, C<UNITCHECK>, C<CHECK>, C<INIT> or C<END> block, or
in a C<DESTROY> method.

This function should have been named wantlist() instead.

=item warn LIST
X<warn> X<warning> X<STDERR>

Prints the value of LIST to STDERR.  If the last element of LIST does
not end in a newline, it appends the same file/line number text as C<die>
does.