From: Robert Klemme <bob.news@...>
Date: 2003-03-19T02:12:05+09:00
Subject: Re: Hash load and GC

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Hi,

I hacked something together using automated marshalling.  Your solution
could then be realized like this:

def getWords()
  InstanceCache.load "words.txt" do |f|
    h={}
    f.each { |line| h[line]=1 }
    h
  end
end

hash = getWords()

Regards

    robert

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=3Dbegin

=3D Synopsis

  This example reads a file into a hash.  Lines must follow the pattern
  "key=3Dvalue".  For this example the difference between parsing =
manually
  and loading via Marshal#load() is approx. 30.

  require 'InstanceCache'

  def get()
    InstanceCache.load "map.txt" do |f|
      h=3D{}

      f.each do |line|
        n, key, value =3D =
*(/^\s*([^\s=3D]+)\s*=3D\s*(.*)$/.match(line).to_a)
        h[key]=3Dvalue if key && value
      end

      h
    end
  end

=3D Description

This module provides for automated loading of instances from a =
marshalled
version if that is newer than a file from which they are otherwise =
parsed.

=3D Module Methods

--- InstanceCache::load( fileName, cacheFileName=3Dnil ) { parser block =
}
    This method loads either from the marshalled version or from the =
file
    denoted by fileName.  If cacheFileName is omitted it  will be build =
by
    appending ".cache" to fileName.

=3D Private Methods

--- InstanceCache::newer?( fileA, fileB )
    Returns true if fileA is newer than fileB or if fileB does not =
exist.

=3Dend

module InstanceCache

  def InstanceCache.load(fileName, cacheFileName=3Dnil, &parser)
    cacheFileName =3D fileName + ".cache" unless cacheFileName

    if newer?(fileName, cacheFileName)
      # need to recache
      puts "recache"
      hash =3D File.open(fileName, &parser)
      File.open(cacheFileName, "w") {|f| Marshal.dump(hash, f)}
      hash
    else
      # load directly
      puts "load"
      File.open(cacheFileName, "r") {|f| Marshal.load(f)}
    end
  end

  private
    def InstanceCache.newer?(fileA, fileB)
      begin
        File.stat(fileA).mtime > File.stat(fileB).mtime
      rescue Errno::ENOENT =3D> e
        e.message =3D~ Regexp.new("\"#{fileB}\"$")
      end
    end

end

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