Hi there, Is the meaning of the ruby error messages defined anywhere? E.g. I get something like: NameError: uninitialized constant Blah and maybe you'll tell me it's self explanatory, but it would be nice to look through a list of errors and read more about what they mean. I searched the web and asked on ruby-lang irc channel but haven't turned up anything yet. Many thanks in advance. CHEERS> SAM
on 2005-11-24 10:02
on 2005-11-24 10:54
Sam J. wrote: > up anything yet. As far as I know there is no such comprehensive list (note, I may be wrong here). But closely looking at the exception stack trace and the code it points to you usually see what's wrong very fast. Kind regards robert
on 2005-11-24 12:51
> NameError: uninitialized constant Blah irb(main):002:0> x = My_case_is_wrong NameError: uninitialized constant My_case_is_wrong from (irb):2 irb(main):003:0> usually, grep -r Blah you_program_dir is make clear the situation.
on 2005-11-24 13:39
On Nov 24, 2005, at 8:01, Sam J. wrote: > searched the web and asked on ruby-lang irc channel but haven't turned > up anything yet. Sounds like a decent wiki page. What it means is that something Ruby considers a constant is being used without being initialised, which I suppose is obvious. The less-obvious bit is "something Ruby considers a constant" which is "an identifier that starts with an uppercase letter". All class and module names, for instance. (Forgive me if that's a little amorphous - I don't have a language grammar to poke through for the actual definition). So, for this error, I would look for typos, particularly in assignment statements (as one poster mentioned), but also in class definitions - maybe you defined your class as "Balh" when you meant "Blah". For particularly tricky cases, you can get a list of constants via 'Module.constants'. matthew smillie.
on 2005-11-24 14:08
Thanks Robert and Yuri, As a ruby newbie I'm finding that I'm getting a little stuck. I've been programming in Java/C like languages for about 15 years, so maybe I'm just having trouble getting used to the brave new world, so perhaps you'll bear with me while I take you through some details. I really like ruby but I'm finding it hard to get to the bottom of things when I do get errors. My current situation involves a module called Gruff. I've mailed my problems to the gruff forums on rubyforge, and we're working on it there, however I'd really like to be able to help solve the problem myself. I've downloaded gruff and rmagick using gems, and I'm trying a gruff code sample in irb (I previously tried an rmagick sample and that works): require 'rubygems' require 'gruff' g = Gruff::Line.new require 'rubygems' returns a fail, and require 'gruff' gives an error, but I can get it to just return false if I comment out the relevant line of code in the gruff source. Anyhow, when I type g = Gruff::Line.new I get the this error: NameError: uninitialized constant Gruff which I presume is telling me that we have failed to pull in the gruff module - adjusting the capitalization is no help: irb(main):004:0> g = gruff::Line.new NameError: undefined local variable or method `gruff' for #<Object:0x2959258> from (irb):4 The thing is I'm stuck as to how to proceed from here - is there some way for me to interogate the system so I can find out why the require 'gruff' is failing? As I understand it my path is set up fine: irb(main):005:0> $: => ["d:/ruby/lib/ruby/gems/1.8/gems/RMagick-win32-1.9.2-mswin32/bin", "d:/ruby/lib/ruby/ge ms/1.8/gems/RMagick-win32-1.9.2-mswin32/lib", "d:/ruby/lib/ruby/gems/1.8/gems/gruff-0.0.6/ bin", "d:/ruby/lib/ruby/gems/1.8/gems/gruff-0.0.6/lib", "d:/ruby/lib/ruby/site_ruby/1.8", "d:/ruby/lib/ruby/site_ruby/1.8/i386-msvcrt", "d:/ruby/lib/ruby/site_ruby", "d:/ruby/lib/r uby/1.8", "d:/ruby/lib/ruby/1.8/i386-mswin32", "."] i.e. i get all the above after entering the require commands, despite the fact that they return failures. hmm, so actually writing all this out helped - as I just fixed the problem. It seems that I needed to restart irb each time I made modifications to the source code in order to see the continuing errors being generated after my modifications. I was confused beacause after throwing an error once, a repeat call to require would just return false, without any error message. By restarting irb and seeing the addtional errors, I commented out a load of undef_method calls in rmagick.rb and now it all works. Sometimes you just need to be able to explain these things to someone :-) Many thanks for your input CHEERS> SAM Robert K. wrote: >As far as I know there is no such comprehensive list (note, I may be wrong >here). But closely looking at the exception stack trace and the code it >points to you usually see what's wrong very fast. > >
on 2005-11-24 14:41
Find Gruff lib. There is a base.rb file. In -------------8<-------8<------------- 1. begin 2. require 'rmagick' 3. rescue LoadError 4. require 'RMagick' # capitalized on Windows 5. end -------------8<-------8<------------- comment out lines 1-3 and 5. Gruff does not deal good with "requre" on Win. Hope this helps you. Pavel