From: Gavin Sinclair <gsinclair@...>
Date: 2002-08-14T08:14:54+09:00
Subject: Re: FileTest module confusion

Some modules are meant for mixing in, some aren't.  FileTest isn't.
Some modules that aren't designed for mixing in can still be useful when mixed
in, others can't.  FileTest can't.

I might be wrong :)

Anyway, to test the existence of a file, choose your weapon:
  FileTest.exists?(path)
  File.stat(path).exists?
  test ?e, path

Cheers,
Gavin


----- Original Message -----
From: "James Toomey" <jamesvtoomey@yahoo.com>
Newsgroups: comp.lang.ruby
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Wednesday, August 14, 2002 3:50 AM
Subject: FileTest module confusion


> I'm just learning Ruby, so please forgive any naivete revealed here.
> In the following code,
> #---------------------------------------
> class DummyClass
>   include FileTest
> end
> DummyInstance = DummyClass.new
> #This works
> puts FileTest.exists?("c:\\autoexec.bat")
> #This doesn't work
> puts DummyInstance.exists?("c:\\autoexec.bat")
> #---------------------------------------
> it seems like the FileTest module acts more like a class than a
> module. From what I've read, modules can be used as "mixins" to
> enhance existing classes but cannot be instantiated on their own.
> However, the opposite seems to be occurring.
> If I substitute the FileTest module for my own module, the expected
> behavior occurs:
> #---------------------------------------
> module SampleModule
>  def displayMessage
>   return "Hello World!"
>  end
> end
> class DummyClass2
>   include SampleModule
> end
> DummyInstance2 = DummyClass2.new
> #This works
> puts DummyInstance2.displayMessage
> #This doesn't work
> puts SampleModule.displayMessage
> #---------------------------------------
> Am I using the FileTest module incorrectly? And if FileTest can be
> used as a standalone object (instead of being mixed in), why isn't it
> a class instead of a module? I know there's the File::Stat object, but
> it seems to operate a bit differently than FileTest.