From: Soichi Ishida <lists@...>
Date: 2013-02-03T10:13:00+09:00
Subject: Class for data analysis: File.open once

ruby 1.9.3p362 (2012-12-25 revision 38607) [x86_64-darwin12.2.1]

I am trying to analyze a file and extract necessary data from it.
First I need to count the total number of lines and the blank lines. the
class and methods follow.

class DataExtractor
    attr_reader :file_name
    def initialize(file)
        @file_name = file
    end

    def total_lines
        @lines = 0
        f = File.open(@file_name, 'r')
        f.read.each_line do |l|
            @lines += 1
        end
        f.close
        @lines
    end

    def total_blank_lines
        regEx = /^[\s]*$\n/
        @total_blank_lines = 0
        f = File.open(@file_name, 'r')
        f.read.each_line do | line |
            if line =~ regEx
                @total_blank_lines += 1
            end
        end
        f.close
        @total_blank_lines
    end
    ....

The problem is that each method has 'File.open...each_line do ' so the
whole loop gets executed separately.

Don't you think this is inefficient?  Is there better ways to develop
methods so that the loop is needed only once?

soichi

-- 
Posted via http://www.ruby-forum.com/.