From: Robert Klemme <shortcutter@...>
Date: 2013-02-15T02:16:27+09:00
Subject: Re: file size of each item in file list

On Thu, Feb 14, 2013 at 12:49 AM, Hassan Schroeder
<hassan.schroeder@gmail.com> wrote:
> On Wed, Feb 13, 2013 at 3:08 PM, Sloan Ruby <lists@ruby-forum.com> wrote:
>> This is what I have now.   I am not able to print out each line of the
>> file /tmp/lg_files.   There is no output.  What am i missing?
>
>> File.read("/tmp/lg_files") do |f|
>> contentsArray=[]  # start with an empty array
>>    f.each_line {|line|
>>    #a = contentsArray.push line
>>         b = File.size contentsArray.last
>>    puts b
>> }
>> end
>
> You've commented out the contentsArray.push line which insures
> that it's always empty, for one thing :-)

Even worse: File.read will ignore the block.  It's simply never
executed.  Otherwise one would see an error.

> Regardless, you don't need that at all. Something like this:
>
> File.open("/tmp/lg_files","r").readlines.each do |line|

Better use

File.foreach "/tmp/lg_files" do |line|

That avoids reading the whole file into memory.

>     line.chomp!;
>     puts "#{line} #{File.size(line)}"
> end

> should do what you want with fewer moving parts.

I think that approach is still more complicated than necessary.  First
of all, the temporary file can be omitted because with IO.popen and
similar methods one can directly read the output of the find command.

It gets even better: one can also do the file system search in Ruby.
There is no point in doing that externally.  There are actually two
ways:
Find.find()
Pathname#find()

Example:

require 'pathname'

Pathname('/var').find do |file|
  printf "%10d %s\n", file.size, file if file.file? && file.size >= 20_000
end

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/