When Perl tries to call an undefined function
    in a particular package and that function is
    not defined, it looks for a function in that
    same package called AUTOLOAD. If one exists,
    it's called with the same arguments as the
    original function would have had.

##</code><code>##

    #!/usr/local/bin/perl -w
    use strict;

    my $code = <<CODE;
    sub foo {
        print "in foo\n";
    }
    CODE

    eval $code;
    foo();

##</code><code>##

    % foo.pl
    in foo