# Generator implementation

**URL:** <https://www.ruby-forum.com/t/generator-implementation/85235>\
**Category:** Ruby\
**Created:** [February 11, 2007, 9:45pm UTC](https://www.ruby-forum.com/t/generator-implementation/85235 "2007-02-11T21:45:47Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Lin\_Jen-Shin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/7993a0/32.png) [@Lin\_Jen-Shin](https://www.ruby-forum.com/u/Lin_Jen-Shin)\
**Post date:** [February 11, 2007, 9:45pm UTC](https://www.ruby-forum.com/t/generator-implementation/85235/1 "2007-02-11T21:45:47Z")

</div>

I was reading the Generator implementation a few hours ago,  
finding out that it’s a little hard to understand the code for me.  
Then I started writing my own implementation with Continuation,  
hoping I understood things well. Did it have to be that complex?

The result was shown below, and they passed the unit tests in  
generator.rb.  
I believed they are faster than the original implementation,  
(p.s. generator.rb,v 1.2.2.2 2004/05/07 08:48:23 matz Exp $)  
but was not sure if there’s something wrong.  
Maybe there’s more consideration I didn’t notice before.  
Please correct me if I lost something. Thank you.

And if you thought this implementation was useful, feel free to use it  
under the same terms as Ruby.

class Generator  
include Enumerable  
def initialize enum = nil, &block  
if enum  
@block = lambda{|g| enum.each{|i| g.yield i}}  
else  
@block = block  
end  
@index = 0  
@value = nil  
if @con\_next = callcc{|c|c}  
@block.call self  
@con\_next.call  
end  
end

```
def next
    raise EOFError, "no more elements available" if end?
    @index += 1
    result = @value
    @con_yield.call if @con_next = callcc{|c|c}
    result
end

def yield value
    @value = value
    @con_next.call if @con_yield = callcc{|c|c}
end

def next?
    return true if @con_yield
    return false
end
def end?
    !next?
end
def index
    @index
end
alias_method :pos, :index
def current
    raise EOFError, "no more elements available" unless @value
    @value
end
def rewind
    initialize &@block
    self
end
def each
    rewind
    yield(self.next) while self.next?
    self
end

```

end

Thank you for reading.