# Log4r and Ruby 1.8.0 in Singleton problems **URL:** \ **Category:** ruby-talk\ **Created:** [5 August 2003 10:17 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224 "2003-08-05T10:17:55Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![David\_Heinemeier\_Ha2](https://avatars.discourse-cdn.com/v4/letter/d/fbc32d/32.png) [@David\_Heinemeier\_Ha2](https://rubytalk.org/u/David_Heinemeier_Ha2)\ **Post date:** [5 August 2003 10:17 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/1 "2003-08-05T10:17:55Z")
Somethings rotten… david% irb irb(main):001:0\> require 'Singleton’ irb(main):002:0\> class Something irb(main):003:1\> include Singleton irb(main):004:1\> end irb(main):005:0\> require ‘log4r’ /usr/local/lib/ruby/1.8/singleton.rb:119: warning: already initialized constant FirstInstanceCall NameError: undefined method `extend_object' for`Singleton’ from /usr/local/lib/ruby/1.8/singleton.rb:161:in `undef_method' from /usr/local/lib/ruby/1.8/singleton.rb:161 from /usr/local/lib/ruby/site_ruby/1.8/log4r/repository.rb:4:in`require’ from /usr/local/lib/ruby/site\_ruby/1.8/log4r/repository.rb:4 from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/ outputterfactory.rb:5:in `require' from /usr/local/lib/ruby/site_ruby/1.8/log4r/outputter/outputterfactory.rb:5 from /usr/local/lib/ruby/site_ruby/1.8/log4r/outputter/outputter.rb:10:in`require’ from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/outputter.rb:10 from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/iooutputter.rb:2:in `require' from /usr/local/lib/ruby/site_ruby/1.8/log4r/outputter/iooutputter.rb:2 from /usr/local/lib/ruby/site_ruby/1.8/log4r/outputter/fileoutputter.rb:4:in`require’ from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/fileoutputter.rb:4 from /usr/local/lib/ruby/site\_ruby/1.8/log4r.rb:8:in `require' from /usr/local/lib/ruby/site_ruby/1.8/log4r.rb:8 from (irb):5:in`require’ from (irb):5 from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/ outputter.rb:118irb(main):006:0\> It doens’t do this unless I make another Singleton-class first. Any got a clue? > **···** > > – > David Heinemeier Hansson, > [http://www.loudthinking.com/](http://www.loudthinking.com/) – Thoughts for free > [http://www.nextangle.com/](http://www.nextangle.com/) – Thoughts for hire ---
**Author:** ![ts1](https://avatars.discourse-cdn.com/v4/letter/t/a8b319/32.png) [@ts1](https://rubytalk.org/u/ts1)\ **Post date:** [5 August 2003 10:38 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/2 "2003-08-05T10:38:20Z")
> irb(main):001:0\> require 'Singleton'                              ^^^^^^^^^ What is this module ? Guy Decoux ---
**Author:** ![Christoph1](https://avatars.discourse-cdn.com/v4/letter/c/85f322/32.png) [@Christoph1](https://rubytalk.org/u/Christoph1)\ **Post date:** [5 August 2003 14:39 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/3 "2003-08-05T14:39:20Z")
David Heinemeier Hansson wrote: > Somethings rotten… > > david% irb > irb(main):001:0\> require ‘Singleton’ > irb(main):002:0\> class Something > irb(main):003:1\> include Singleton > irb(main):004:1\> end > irb(main):005:0\> require ‘log4r’ > /usr/local/lib/ruby/1.8/singleton.rb:119: warning: already initialized > constant FirstInstanceCall > NameError: undefined method `extend_object' for `Singleton’ On windows you will get the same error message. However, if you write > **···** > > * * * > > ## require ‘singleton’ class A include Singleton end require ‘log4r’ > > you’ll be fine. My guess is that ruby `thinks'' that `Singleton.rb" > and `singleton.rb" (in my case installed in E:/Ruby/lib/ruby/1.8) are different files - however in the windows world or on a Macs HFS+ file-system `Singleton.rb" and ``singleton.rb’’ refer to the > same file. > > This difference results in unnecessary reload of ``singleton.rb’’ > which in turn triggers the NameError of Ruby trying to undefine > an already undefined method (extend\_object). > > I suggest that you consistently use the lower case version require > ‘singleton’. Alternatively change the line > > 161 \> undef\_method :extend\_object > > in singleton.rb to > > 161 \> undef\_method :extend\_object unless defined? :extend\_object > > /Christoph ---
**Author:** ![David\_Heinemeier\_Ha2](https://avatars.discourse-cdn.com/v4/letter/d/fbc32d/32.png) [@David\_Heinemeier\_Ha2](https://rubytalk.org/u/David_Heinemeier_Ha2)\ **Post date:** [5 August 2003 10:51 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/4 "2003-08-05T10:51:40Z")
> > irb(main):001:0\> require ‘Singleton’ > > ^^^^^^^^^ > > What is this module ? I’m sorry. I recreated the test case too quickly (and wrong). Here’s a better one: log4r.rbx: require ‘log4r’ Log = Log4r::Logger.new(“AC”) Log.add Log4r::StderrOutputter.new ‘console’ …which produce: /usr/local/lib/ruby/1.8/singleton.rb:161:in `undef_method': undefined method `extend\_object’ for `Singleton' (NameError) from /usr/local/lib/ruby/1.8/singleton.rb:161 from /usr/local/lib/ruby/1.8/auto-reload.rb:77:in `load’ from /usr/local/lib/ruby/1.8/auto-reload.rb:77:in `require' from /usr/local/lib/ruby/site_ruby/1.8/log4r/repository.rb:4 from /usr/local/lib/ruby/1.8/auto-reload.rb:77:in `load’ from /usr/local/lib/ruby/1.8/auto-reload.rb:77:in `require' from /usr/local/lib/ruby/site_ruby/1.8/log4r/outputter/outputterfactory.rb:5 from /usr/local/lib/ruby/1.8/auto-reload.rb:77:in `load’ … 12 levels… from /usr/local/lib/ruby/1.8/auto-reload.rb:77:in `require' from /Users/david/Sites/extranet/log4r.rbx:1 from /usr/local/lib/ruby/1.8/apache/ruby-run.rb:53:in `load’ from /usr/local/lib/ruby/1.8/apache/ruby-run.rb:53:in `handler’ The contents of log4r.rbx works fine if used in IRB, but not under mod\_ruby. / David ---
**Author:** ![ts1](https://avatars.discourse-cdn.com/v4/letter/t/a8b319/32.png) [@ts1](https://rubytalk.org/u/ts1)\ **Post date:** [5 August 2003 11:01 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/5 "2003-08-05T11:01:01Z")
> log4r.rbx: ruby is trying to load \*twice\* the same module 'singleton.rb' : it do this because it don't have the same path, or name, or version, for singleton.rb svg% cat b.rb #!/usr/bin/ruby require 'singleton' class Something    include Singleton end require 'log4r' svg% svg% b.rb svg% Now svg% cat b.rb #!/usr/bin/ruby require '/usr/local/lib/ruby/1.8/singleton.rb' class Something    include Singleton end require 'log4r' svg% svg% b.rb /usr/local/lib/ruby/1.8/singleton.rb:119: warning: already initialized constant FirstInstanceCall /usr/local/lib/ruby/1.8/singleton.rb:161:in `undef_method': undefined method `extend\_object' for `Singleton' (NameError)         from /usr/local/lib/ruby/1.8/singleton.rb:161         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/repository.rb:4:in `require'         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/repository.rb:4         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/outputterfactory.rb:5:in `require'         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/outputterfactory.rb:5         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/outputter.rb:10:in `require'         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/outputter.rb:10         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/iooutputter.rb:2:in `require'         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/iooutputter.rb:2         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/fileoutputter.rb:4:in `require'         from /usr/local/lib/ruby/site\_ruby/1.8/log4r/outputter/fileoutputter.rb:4         from /usr/local/lib/ruby/site\_ruby/1.8/log4r.rb:8:in `require'         from /usr/local/lib/ruby/site\_ruby/1.8/log4r.rb:8         from ./b.rb:6:in `require'         from ./b.rb:6 svg% For ruby    require '/usr/local/lib/ruby/1.8/singleton.rb' is different (it think that it's another module)    require 'singleton' # which is in repository.rb This is why it give an error Another reason is that you mix    \* ruby 1.8.0    \* mod\_ruby built with ruby 1.6.8 Guy Decoux ---
**Author:** ![David\_Heinemeier\_Ha2](https://avatars.discourse-cdn.com/v4/letter/d/fbc32d/32.png) [@David\_Heinemeier\_Ha2](https://rubytalk.org/u/David_Heinemeier_Ha2)\ **Post date:** [5 August 2003 11:22 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/6 "2003-08-05T11:22:39Z")
> For ruby > > require ‘/usr/local/lib/ruby/1.8/singleton.rb’ > > is different (it think that it’s another module) > > require ‘singleton’ # which is in repository.rb > > This is why it give an error Right. But the log4r.rbx doesn’t contain any requirements to include the singleton module more than once. It’s _only_ those three lines: require ‘log4r’ Log = Log4r::Logger.new(“AC”) Log.add Log4r::StderrOutputter.new ‘console’ …and since those three lines work just fine in IRB, I suspect something fishy with mod\_ruby. > Another reason is that you mix > > - ruby 1.8.0 > - mod\_ruby built with ruby 1.6.8 I didn’t. Just double-checked it and even recompiled mod\_ruby (1.1.1) and installed it again. It’s surely ruby 1.8.0 and mod\_ruby 1.1.1 compiled with the same version. (Thanks for the suggestions, though…) / David ---
**Author:** ![Dave\_Mail\_Archive](https://avatars.discourse-cdn.com/v4/letter/d/f04885/32.png) [@Dave\_Mail\_Archive](https://rubytalk.org/u/Dave_Mail_Archive)\ **Post date:** [5 August 2003 14:09 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/7 "2003-08-05T14:09:19Z")
ts wrote: > For ruby > > require ‘/usr/local/lib/ruby/1.8/singleton.rb’ > > is different (it think that it’s another module) > > require ‘singleton’ # which is in repository.rb > > This is why it give an error I have never understood this: why doesn’t Ruby store the cannonical (fully expanded) path name; that would eliminate this kind of problem. ---
**Author:** ![Brian\_Candler](https://avatars.discourse-cdn.com/v4/letter/b/5f9b8f/32.png) [@Brian\_Candler](https://rubytalk.org/u/Brian_Candler)\ **Post date:** [5 August 2003 11:43 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/8 "2003-08-05T11:43:52Z")
ruby 1.8.0 installs its libraries in a different place… so just to be sure, try puts RUBY\_VERSION in your mod\_ruby application and see what it reports. Cheers, Brian. > **···** > > On Tue, Aug 05, 2003 at 08:22:39PM +0900, David Heinemeier Hansson wrote: > > > > Another reason is that you mix > > > > > > - ruby 1.8.0 > > > - mod\_ruby built with ruby 1.6.8 > > > > I didn’t. Just double-checked it and even recompiled mod\_ruby (1.1.1) > > and installed it again. It’s surely ruby 1.8.0 and mod\_ruby 1.1.1 > > compiled with the same version. ---
**Author:** ![ts1](https://avatars.discourse-cdn.com/v4/letter/t/a8b319/32.png) [@ts1](https://rubytalk.org/u/ts1)\ **Post date:** [5 August 2003 11:51 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/9 "2003-08-05T11:51:11Z")
> Right. But the log4r.rbx doesn't contain any requirements to include > the singleton module more than once. It's \_only\_ those three lines: What is your complete configuration. I can reproduce it with auto-load svg% ruby -rauto-reload -rlog4r -rsingleton -e 1 /usr/local/lib/ruby/1.8/singleton.rb:119: warning: already initialized constant FirstInstanceCall /usr/local/lib/ruby/1.8/singleton.rb:161:in `undef_method': undefined method `extend\_object' for `Singleton' (NameError)         from /usr/local/lib/ruby/1.8/singleton.rb:161 svg% > I didn't. Just double-checked it and even recompiled mod\_ruby (1.1.1) > and installed it again. It's surely ruby 1.8.0 and mod\_ruby 1.1.1 > compiled with the same version. The apache server was restarted ? Try to give it the command     HEAD / HTTP/1.0 to see what it say Guy Decoux ---
**Author:** ![Marko\_Schulz](https://avatars.discourse-cdn.com/v4/letter/m/aca169/32.png) [@Marko\_Schulz](https://rubytalk.org/u/Marko_Schulz)\ **Post date:** [5 August 2003 14:35 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/10 "2003-08-05T14:35:02Z")
I always thought this isn’t done, so the programmer isn’t deluded a false sense of security: There isn’t always _the_ cannonical path. Think of filesystems that ignore the case in filenames. (Not to mention (symbolic and hard) links or alias names (single~1.rb) > **···** > > On Tue, Aug 05, 2003 at 11:09:19PM +0900, Dave Thomas wrote: > > > ts wrote: > > > > > require ‘/usr/local/lib/ruby/1.8/singleton.rb’ > > > > > > is different (it think that it’s another module) > > > > > > require ‘singleton’ # which is in repository.rb > > > > I have never understood this: why doesn’t Ruby store the cannonical > > (fully expanded) path name; that would eliminate this kind of problem. > > – > marko schulz ---
**Author:** ![David\_Heinemeier\_Ha2](https://avatars.discourse-cdn.com/v4/letter/d/fbc32d/32.png) [@David\_Heinemeier\_Ha2](https://rubytalk.org/u/David_Heinemeier_Ha2)\ **Post date:** [5 August 2003 11:55 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/11 "2003-08-05T11:55:46Z")
> ruby 1.8.0 installs its libraries in a different place… so just to be > sure, try > puts RUBY\_VERSION > in your mod\_ruby application and see what it reports. I’ve reduced the test case to this: singleton.rbx: require “singleton” That doesn’t work (same complaining about trying to import the same class twice). This does, though: require “/usr/local/lib/ruby/1.6/singleton.rb” But “puts RUBY\_VERSION” from a .rbx gives me 1.8.0, so it must be running from the newest version. But mod\_ruby is obviously still using the 1.6 singleton.rb file. I just can’t figure out why. / David ---
**Author:** ![David\_Heinemeier\_Ha2](https://avatars.discourse-cdn.com/v4/letter/d/fbc32d/32.png) [@David\_Heinemeier\_Ha2](https://rubytalk.org/u/David_Heinemeier_Ha2)\ **Post date:** [5 August 2003 12:05 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/12 "2003-08-05T12:05:27Z")
> What is your complete configuration. I can reproduce it with auto-load OS X 10.2.6, mod\_ruby 1.1.1, Apache 1.3.27, ruby 1.8.0 > The apache server was restarted ? Yearh. I even rebooted the entire machine. > Try to give it the command > > ``` > HEAD / HTTP/1.0 > > ``` HTTP/1.1 200 OK Server: Apache/1.3.27 (Darwin) mod\_ruby/1.1.1 PHP/4.3.2 Content-Type: text/html (Thanks again for helping me to locate this…) / David > **···** > > Date: Tue, 05 Aug 2003 12:03:17 GMT ---
**Author:** ![Dave\_Mail\_Archive](https://avatars.discourse-cdn.com/v4/letter/d/f04885/32.png) [@Dave\_Mail\_Archive](https://rubytalk.org/u/Dave_Mail_Archive)\ **Post date:** [5 August 2003 14:46 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/13 "2003-08-05T14:46:07Z")
Marko Schulz wrote: > > I have never understood this: why doesn’t Ruby store the cannonical > > (fully expanded) path name; that would eliminate this kind of problem. > > I always thought this isn’t done, so the programmer isn’t deluded a > false sense of security: There isn’t always _the_ cannonical > path. Think of filesystems that ignore the case in filenames. (Not to > mention (symbolic and hard) links or alias names (single~1.rb) 1. Would it be worse than it is now? 2. Why couldn’t Ruby make the name cannonical. On a Unix-based box, for example, it could store the i-node number. Surely every operating system has _some_ way to get to a single target identifier for a given file? Cheers Dave ---
**Author:** ![Ben\_Giddings](https://avatars.discourse-cdn.com/v4/letter/b/b19c9b/32.png) [@Ben\_Giddings](https://rubytalk.org/u/Ben_Giddings)\ **Post date:** [5 August 2003 14:50 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/14 "2003-08-05T14:50:07Z")
I see the argument, but I don’t really like it. One thing I like about Java (which seems more OO than Ruby) is that when you import something, what you’re specifying is classes rather than files. I like this idea because the classes are what you really care about anyhow. Another problem which is starting to pop up is versioning. In Perl you can require that what you’re using has a certain version number. This is a good “sanity check” when you’re using libraries which may fluctuate (like the CGI one for example). Is it too late to come up with an alternative to ‘require’? Ben > **···** > > On Tuesday, August 5, 2003, at 10:35 AM, Marko Schulz wrote: > > > On Tue, Aug 05, 2003 at 11:09:19PM +0900, Dave Thomas wrote: > > > > > I have never understood this: why doesn’t Ruby store the cannonical > > > (fully expanded) path name; that would eliminate this kind of problem. > > > > I always thought this isn’t done, so the programmer isn’t deluded a > > false sense of security: There isn’t always _the_ cannonical > > path. Think of filesystems that ignore the case in filenames. (Not to > > mention (symbolic and hard) links or alias names (single~1.rb) ---
**Author:** ![Mauricio\_Fernndez](https://avatars.discourse-cdn.com/v4/letter/m/e495f1/32.png) [@Mauricio\_Fernndez](https://rubytalk.org/u/Mauricio_Fernndez)\ **Post date:** [5 August 2003 15:01 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/15 "2003-08-05T15:01:44Z")
> I see the argument, but I don’t really like it. One thing I like about > Java (which seems more OO than Ruby) is that when you import something, > what you’re specifying is classes rather than files. I like this idea Only because Java enforces a given directory structure. If you had the same constraint in Ruby, require would be similar to import. > Is it too late to come up with an alternative to ‘require’? Nothing prevents you from writing it, making it compatible with require and getting some people to use it 🙂 > **···** > > On Tue, Aug 05, 2003 at 11:50:07PM +0900, Ben Giddings wrote: > > – > \_ \_ > > > > \_\_ \_\_ _| |_ \_\_\_ \_ \_\_ \_\_\_ \_\_ \_ \_ \_\_ > > > '\_ \ / _`| __/__ | '_` \_ \ / ` | ’ \ > > > ) | (| | |_\_\_ \ | | | | | (_| | | | | > > > .\_\_/ \_,_|\ __|__ /| |_| |_|\__,_|_| |\_| > > > Running Debian GNU/Linux Sid (unstable) > > > batsman dot geo at yahoo dot com > > How do you power off this machine? > – Linus, when upgrading [linux.cs.helsinki.fi](http://linux.cs.helsinki.fi), and after using the machine for several months ---
**Author:** ![Mark\_J\_Reed](https://avatars.discourse-cdn.com/v4/letter/m/f6c823/32.png) [@Mark\_J\_Reed](https://rubytalk.org/u/Mark_J_Reed)\ **Post date:** [5 August 2003 15:19 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/16 "2003-08-05T15:19:29Z")
> > I always thought this isn’t done, so the programmer isn’t deluded a > > false sense of security: There isn’t always _the_ cannonical > > path. Think of filesystems that ignore the case in filenames. (Not to > > mention (symbolic and hard) links or alias names (single~1.rb) > 1. Would it be worse than it is now? Depends on whether you think false security is better than no security. 🙂 > 1. Why couldn’t Ruby make the name cannonical. On a Unix-based > box, for example, it could store the i-node number. Technically, it would have to be the pair (device, i-node number), but it’s a good thought. If the file to be loaded has the same (d,i) as a file already loaded, don’t load it again. It would require more OS-specific code in the loader, though. > Surely every operating system > has _some_ way to get to a single target identifier for a given file? I would be wary of making such an assumption. It seems logical, but OSes are often illogical creatures, at least on the surface. 🙂 -Mark > **···** > > On Tue, Aug 05, 2003 at 11:46:07PM +0900, Dave Thomas wrote: ---
**Author:** ![Marko\_Schulz](https://avatars.discourse-cdn.com/v4/letter/m/aca169/32.png) [@Marko\_Schulz](https://rubytalk.org/u/Marko_Schulz)\ **Post date:** [5 August 2003 16:06 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/17 "2003-08-05T16:06:46Z")
> Marko Schulz wrote: > > > > I have never understood this: why doesn’t Ruby store the cannonical > > > (fully expanded) path name; that would eliminate this kind of problem. > > > > I always thought this isn’t done, so the programmer isn’t deluded a > > false sense of security: There isn’t always _the_ cannonical > > path. Think of filesystems that ignore the case in filenames. (Not to > > mention (symbolic and hard) links or alias names (single~1.rb) > > 1. Would it be worse than it is now? If there is a solution: Great! I don’t really have enough cross-platform knowledge to decide whether it is possible; but on the platforms I know, it already seems awkward, to detect for sure, whether a file already has been read (maybe somebody should look how others do it): > 1. Why couldn’t Ruby make the name cannonical. On a Unix-based box, for > example, it could store the i-node number. Besides the number of the i-node you would at least have to store the mount point (or the device?). Here I have to files on different devices with the same inode: $ ls -di /usr/include/netax25 /home/marko/musik/Farin\_Urlaub/Endlich\_Urlaub 374641 /home/marko/musik/Farin\_Urlaub/Endlich\_Urlaub 374641 /usr/include/netax25 But even then, I wouldn’t be sure, that every filesystem on every unices uses reliable i-node numbers. Under Linux they are at least not stable across remounts for a FAT-FS: $ ls -i /mnt/dos/autoexec.bat 67756 /mnt/dos/autoexec.bat $ sudo umount /mnt/dos/ $ sudo mount /mnt/dos/ $ ls -i /mnt/dos/autoexec.bat 67757 /mnt/dos/autoexec.bat > Surely every operating system > has _some_ way to get to a single target identifier for a given file? Maybe just storing the full path is already enough (resolving all …/'s and maybe symlinks). Maybe storing a md5sum for each file is enough. Maybe somebody just has to try it. > **···** > > On Tue, Aug 05, 2003 at 11:46:07PM +0900, Dave Thomas wrote: > > – > marko schulz ---
**Author:** ![Brian\_Candler](https://avatars.discourse-cdn.com/v4/letter/b/5f9b8f/32.png) [@Brian\_Candler](https://rubytalk.org/u/Brian_Candler)\ **Post date:** [5 August 2003 16:24 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/18 "2003-08-05T16:24:16Z")
> I don’t really have enough cross-platform knowledge to decide whether > it is possible; but on the platforms I know, it already seems awkward, > to detect for sure, whether a file already has been read (maybe > somebody should look how others do it): In C, the file itself is responsible for this: #ifndef \_myheader\_h #define \_myheader\_h … do stuff #endif > Maybe storing a md5sum for each file is enough. Cool idea, except the cost of reading in a file every time you see require ‘foo’ means that it would break things. I quite happily put a ‘require’ buried inside a loop at the moment, knowing that the library will get read just the first time it’s needed. Cheers, Brian. > **···** > > On Wed, Aug 06, 2003 at 01:06:46AM +0900, Marko Schulz wrote: ---
**Author:** ![Gavin\_Sinclair](https://avatars.discourse-cdn.com/v4/letter/g/db5fbb/32.png) [@Gavin\_Sinclair](https://rubytalk.org/u/Gavin_Sinclair)\ **Post date:** [5 August 2003 22:55 UTC](https://rubytalk.org/t/log4r-and-ruby-1-8-0-in-singleton-problems/7224/19 "2003-08-05T22:55:10Z")
You would also need the constraint that files and classes be named the same. I am tending towards that constraint in my own code anyway, primarily so the target of ‘require’ resolves as a ctag, easing navigation. Another difference between Java and Ruby here: Java allows only one “public” class in each file. Not that Ruby has the concept of packages anyway. Gavin > **···** > > On Wednesday, August 6, 2003, 1:01:44 AM, Mauricio wrote: > > > On Tue, Aug 05, 2003 at 11:50:07PM +0900, Ben Giddings wrote: > > > > > I see the argument, but I don’t really like it. One thing I like about > > > Java (which seems more OO than Ruby) is that when you import something, > > > what you’re specifying is classes rather than files. I like this idea > > > Only because Java enforces a given directory structure. If you had the > > same constraint in Ruby, require would be similar to import.