From: "s.ross" <cwdinfo@...>
Date: 2008-02-21T09:09:42+09:00
Subject: Re: Is there any object-oriented File class in ruby ?

On Feb 20, 2008, at 1:29 PM, tom_33 wrote:
> However, an important difference with ruby File class and the java
> File class is that the java class provides a cohesive unit of instance
> methods that encapsulates a file path, without having to provide a
> string as parameter to every method.

Path name parsing aside -- which is really a small part of what File  
does -- here are some comments.

To open and read each line in a file, do this:

File.open(filename, mode) do |f|
   f.each {|line| #do something with the line}
end

Notice that the file is opened and a block yielding the context of the  
open file is used thereafter for file manipulation. There are a bunch  
of filesystem interrogation methods that are, by their nature, better  
handled by passing strings. Why? Because often you don't want to open  
a file just to find out when it was modified or what its basename is.  
That's why there are so many class methods (or, if you prefer, "static  
functions").

Encapsulation is about keeping your data in a safe place where the  
implementation of the data store is abstracted. Access is through  
methods that don't change. It's conceivable that you could create a  
class to wrap the File functions like:

class FileTools
   def initialize(file_name)
     @file_name = file_name
   end

   def basename
     File.basename(@file_name)
   end

   def atime
     File.atime(@file_name)
   end

   # etc.
end

Then you would need to do this in your code:

f = FileTools.new('my.file')
basename = f.basename
last_accessed = f.atime

I don't typically use a ton of these methods, so specifying the string  
each time isn't a huge burden. Creating a new object just so you can  
interrogate the filesystem seems like overkill -- it's unlikely the  
interface to the filesystem will change any time soon.

Just my $.02