Re^2: Circular buffer

[mellon85]

in reply to Re: Circular buffer
in thread Circular buffer

I don't like leaving the $pointer variable grow indefinitely.
This code is equivalent, but keeps $pointer in [0,@buffer). In fact, just gets the remainder after each $pointer change

my @buffer = (0) x 5;
my $pointer = 0;
for (0..30) {
    print "old value: ", $buffer[$pointer], "\n";
    print "new value: $_\n";
    $buffer[$pointer] = $_; 
    $pointer = (++$pointer) % @buffer;
}

[moritz]

I usually avoid code like $pointer = (++$pointer) % @buffer; where the same variable is modified twice within the same expression. It means that the outcome depends on the order of evaluation, which isn't defined in all cases (it is in the case of assignment though).

Instead I'd just write $pointer = (1 + $pointer) % @buffer.

[repellent]

No $pointer. @buffer always ordered last to most recent.


my @buffer = (0) x 5;
for (0..30) {
    print "old value: ", $buffer[0], "\n";
    print "new value: $_\n";
    shift @buffer;
    push  @buffer, $_;
}