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October 29, 2018 12:00
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A simple ring buffer for Ruby.
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class RingBuffer < Array | |
attr_reader :max_size | |
def initialize(max_size, enum = nil) | |
@max_size = max_size | |
enum.each { |e| self << e } if enum | |
end | |
def <<(el) | |
if self.size < @max_size || @max_size.nil? | |
super | |
else | |
self.shift | |
self.push(el) | |
end | |
end | |
alias :push :<< | |
end |
I fixed this on my fork, https://gist.github.com/4078106
@Nimster: many thanks for pointing it out, fixed. I'm still very much a Ruby newbie, and certainly much more so when I originally created this Gist.
Also check out this threadsafe one http://git.io/8RZjeA
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This has a major bug. << by default means "push", so
a = RingBuffer.new(3)
a << "first"
a << "second"
a << "third" # a == ["first", "second", "third"]
# but now
a << "fourth" # a == ["fourth", "first", "second"]
Where one would expect after the fourth insertion, a would contain ["second", "third", "fourth"]. This is consistent with a RingBuffer being a data structure for MRU access, i.e oldest elements should be overwritten.