From: Chris Gernon <kabigon@...>
Date: 2007-01-31T02:50:00+09:00
Subject: Re: Correct way to process a file in Ruby?

Dave Hatton wrote:
> What is the correct way to code the following in Ruby?
> 
> open file
> read field from file
> determine from field the type of file
> case file type in
>    type 1) do this (lots of stuff)
>    type 2) do that (even more stuff)
>    type 3) do something else (you get the picture)
>         *) error
> esac
> close file

You shouldn't need to open/close the file more than once. Unless I'm 
misunderstanding something, you should be able to just do something like 
this:

File.open('huge.txt') do |file|
  first_line = file.gets
  file_type = determine_file_type(first_line)
  case file_type
  when 'csv': process_csv(file)
  when 'tab_delimited': process_tab(file)
  else
    puts "Error! OMG!"
  end
end

def process_csv(file)
  file.each do |line|
    # do something with the line
  end
end

The main File.open block handles the opening and closing of the file, 
and you just pass the file handle to the methods that do the actual 
processing. Nice and simple.

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