instiki/vendor/rails/activesupport/lib/active_support/whiny_nil.rb
Jacques Distler 6873fc8026 Upgrade to Rails 2.0.2
Upgraded to Rails 2.0.2, except that we maintain

   vendor/rails/actionpack/lib/action_controller/routing.rb

from Rail 1.2.6 (at least for now), so that Routes don't change. We still
get to enjoy Rails's many new features.

Also fixed a bug in Chunk-handling: disable WikiWord processing in tags (for real this time).
2007-12-21 01:48:59 -06:00

39 lines
1.3 KiB
Ruby

# Extensions to nil which allow for more helpful error messages for
# people who are new to rails.
#
# The aim is to ensure that when users pass nil to methods where that isn't
# appropriate, instead of NoMethodError and the name of some method used
# by the framework users will see a message explaining what type of object
# was expected.
class NilClass
WHINERS = [::Array]
WHINERS << ::ActiveRecord::Base if defined? ::ActiveRecord
@@method_class_map = Hash.new
WHINERS.each do |klass|
methods = klass.public_instance_methods - public_instance_methods
class_name = klass.name
methods.each { |method| @@method_class_map[method.to_sym] = class_name }
end
def id
raise RuntimeError, "Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id", caller
end
private
def method_missing(method, *args, &block)
raise_nil_warning_for @@method_class_map[method], method, caller
end
def raise_nil_warning_for(class_name = nil, selector = nil, with_caller = nil)
message = "You have a nil object when you didn't expect it!"
message << "\nYou might have expected an instance of #{class_name}." if class_name
message << "\nThe error occurred while evaluating nil.#{selector}" if selector
raise NoMethodError, message, with_caller || caller
end
end