http://www.perlmonks.org?node_id=910294


in reply to Re^2: Dumb, non-question: How to return 'nothing'.
in thread Dumb, non-question: How to return 'nothing'.

That's a nice solution, but is there any particular reason to use an arrayref rather than a scalarref?

Its copy/paste from the book, the first solution -- I guess its more generic, re-usability and all that :)

  • Comment on Re^3: Dumb, non-question: How to return 'nothing'.

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Re^4: Dumb, non-question: How to return 'nothing'.
by ikegami (Patriarch) on Jun 18, 2011 at 05:53 UTC

    Seeing as a scalar is always being returned, 

    while( my $next = $iter->() ) {
    ($next) = @$next;
    ...
}

    [download]

    can be shortened to 

    while( my ($next) = @{ $iter->() } ) {
    ...
}

    [download]
[reply]
[d/l]
[select]
[reply]

        No, the loop won't exit even if [ undef ] or [ 0 ] is returned. List assignment in scalar context returns the number of elements to which its RHS evaluates, meaning the number of elements in the array.

        You'd be right that 

        while( my $next = $iter->() ) {
    my @next = @$next;
    ...
}

        [download]

        is not equivalent to 

        while( my @next = @{ $iter->() } ) {
    ...
}

        [download]

        But that's not the situation here.

        The point was that 

        while( my $next = $iter->() ) {
    ($next) = @$next;
    ...
}

        [download]

        is a complicated version of 

        while( my $next = @{ $iter->() } ) {
    ...
}

        [download]

        which is just an expensive version of 

        while( my ($next) = $iter->() ) {
    ...
}

        [download]
[reply]
[d/l]
[select]

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