Your example code takes a reference to each individual list element returned by foo(), and then retains the last one.

If you want a reference to an array, you have two choices. First, you could modify the subroutine to return a reference to an array:

sub foo { return [0,1]; }
my $aref = foo();

[download]

Second, you could instantiate an array reference upon receiving the return value of the subroutine:

sub foo { return (0,1); }
my $aref = [foo()];

[download]

In the second example, the [...] square brackets are creating a reference to an anonymous array that is being populated by the list returned from foo().

For large lists, the first example could be more efficient since it passes a single value (the array reference) back from the subroutine call, rather than a potentially large list which must then be pulled into a new reference. We all love to hate wantarray, but how about this?

sub foo {
    my @rv = (0,1);
    return wantarray() ? @rv : \@rv;
}
my $aref  = [foo()]; # wantarray() will be true, so the entire list ge
+ts passed back and then the square braces create and populate an arra
+y ref.
my $aref2 = foo();   # wantarray() will be false, so inside the subrou
+tine we return a reference to the array.

[download]

Yeah.... that code kind of smells because it has a strong potential of surprising the caller. Just a thought, but you'll probably want the first or second example and just keep the third as an example of something that Perl can do but maybe shouldn't. ;)


Dave

In reply to Re: Reference to return value of a subroutine by davido
in thread Reference to return value of a subroutine by Christina

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