in reply to Re: iterator w/ wantarray()
in thread iterator w/ wantarray()

Problem solved

I realized that it is a closure!

You are right. The sub counter is modified like this and it works OK.
Thank you for your help. 

#
# My fixed counter() 
#
sub counter {
    my ($from, $to, $step)= @_;
    $step ||= 1;

    return sub {
        return if $from > $to;
        my $value=$from;
        $from +=$step;
        return $value;
    };
}

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Re^3: iterator w/ wantarray()
by tobyink (Canon) on Apr 27, 2020 at 07:09 UTC

    This would be a more normal way of doing it. Don't change $from but close over $value.

    #
# My fixed counter()
#
sub counter {
    my ($from, $to, $step) = @_;
    $step //= 1;
    my $value = $from;

    return sub {
        return if $value > $to;
        $value += $step;
    };
}

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