# add new columns to an existing row
push @{ $AoA[0] }, "wilma", "betty"; # explicit deref
-Prior to Perl 5.14, this wouldn't even compile:
-
- push $AoA[0], "wilma", "betty"; # implicit deref
-
-How come? Because once upon a time, the argument to push() had to be a
-real array, not just a reference to one. That's no longer true. In fact,
-the line marked "implicit deref" above works just fine--in this
-instance--to do what the one that says explicit deref did.
-
-The reason I said "in this instance" is because that I<only> works
-because C<$AoA[0]> already held an array reference. If you try that on an
-undefined variable, you'll take an exception. That's because the implicit
-derefererence will never autovivify an undefined variable the way C<@{ }>
-always will:
-
- my $aref = undef;
- push $aref, qw(some more values); # WRONG!
- push @$aref, qw(a few more); # ok
-
-If you want to take advantage of this new implicit dereferencing behavior,
-go right ahead: it makes code easier on the eye and wrist. Just understand
-that older releases will choke on it during compilation. Whenever you make
-use of something that works only in some given release of Perl and later,
-but not earlier, you should place a prominent
-
- use v5.14; # needed for implicit deref of array refs by array ops
-
-directive at the top of the file that needs it. That way when somebody
-tries to run the new code under an old perl, rather than getting an error like
-
- Type of arg 1 to push must be array (not array element) at /tmp/a
- line 8, near ""betty";"
- Execution of /tmp/a aborted due to compilation errors.
-
-they'll be politely informed that
-
- Perl v5.14.0 required--this is only v5.12.3, stopped at /tmp/a line 1.
- BEGIN failed--compilation aborted at /tmp/a line 1.
-
=head2 Access and Printing
Now it's time to print your data structure out. How
[ "george", "jane", "elroy" ],
[ "homer", "marge", "bart" ],
);
- push $AoA[0], "wilma", "betty";
+ push @{ $AoA[0] }, "wilma", "betty";
show @AoA;
will print out: