From: Daniel Berger <djberg96@...>
Date: 2006-01-01T10:57:56+09:00
Subject: Re: Memoization, files and Marshal?

ara.t.howard@noaa.gov wrote:
> On Sun, 1 Jan 2006, Daniel Berger wrote:

<snip>

>    harp:~ > cat a.rb
>    def memoize_to_file(name, file)
>      cache = Hash.new.update(Marshal.load(File.read(file))) rescue {}
>      (class << self; self; end).class_eval do
>         define_method(name) do |*args|
>            unless cache.has_key?(args)
>              cache[args] = method(name).call(*args)
>              File.open(file, "wb+"){|f| Marshal.dump(cache, f) }
>            end
>            cache[args]
>         end
>      end
>    end
>
>    def fib(n)
>     return n if n < 2
>     fib(n-1) + fib(n-2)
>    end
>
>    memoize_to_file "fib", "fib.cache"
>    n = fib 10
>    p n

As is, I get a stack level too deep error on Windows.  If I change the
"cache[args] =" to "cache[args] ||=", I always get back nil.

I'm probably being thick here, but any help is appreciated.

Thanks,

Dan