I’m just getting started with rails and have run into a problem with
class names. If I create a class, and call it MyClass, it throws the
following error.
@my_class = MyClass.new
NameError: uninitialized constant MyClass
from /Library/Ruby/Gems/1.8/gems/activesupport-2.0.2/lib/
active_support/dependencies.rb:266:in load_missing_constant' from /Library/Ruby/Gems/1.8/gems/activesupport-2.0.2/lib/ active_support/dependencies.rb:453:inconst_missing’
from /Library/Ruby/Gems/1.8/gems/activesupport-2.0.2/lib/
active_support/dependencies.rb:465:in `const_missing’
from (irb):47
However, if I rename it Myclass (note the capitalisation), it works:
Is it supposed to work like this? I am using Rails 2.0.2 on Mac OS X
Leopard 10.5.2
(Simplifying slightly) When rails hits a const_missing, it will
underscorize the class name and try and load that file. So when it
hits MyClass it will look for my_class.rb and if it hits Myclass it
will look for myclass.rb. Either is fine, but don’t mix and match: it
sounds like you’ve got MyClass in a file named my_class
That’s interesting. The MyClass file was called MyClass.rb. I’ve just
tried naming the file to My_Class.rb (with the class still called
MyClass) , and then it works. Therefore I guess I should underscorize
any capitalized class files?
That’s interesting. The MyClass file was called MyClass.rb. I’ve just
tried naming the file to My_Class.rb (with the class still called MyClass)
, and then it works. Therefore I guess I should underscorize any
capitalized class files?
You should generally name everything exactly following the patterns
you
will find in ‘script/generate model’, in the various Rails books, in the
scaffold generators, and in the blogosphere. script/generate model
my_class
will create my_class.rb, containing class MyClass. Your tweak,
My_Class.rb,
might not work on case-sensitive filesystems. (But then it might work
anyway, because I thought Leopard was a Un*x in a fuzzy spotted coat).
Rails is opinionated, and works best when it can configure by
convention.
(Compare the agony of systems that configure via endless ANT and
property
files…) But that’s not the only reason to follow all these
conventions.
All projects should have a consistent coding style. The best source for
this
is your main library. So when in Rome, do as the Romans do!
