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authorXavier Noria <fxn@hashref.com>2013-12-06 19:13:51 +0100
committerXavier Noria <fxn@hashref.com>2013-12-06 19:18:10 +0100
commit01c9782fa2392729bea08409e348fe049857d9d6 (patch)
treed4ef12c78ce6e98e77093e36573bf1c7728012e6 /activesupport
parent8ef1ef1b822cdb49e72edd16a8ddbc67e5e1cf94 (diff)
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better error message for constants autoloaded from anonymous modules [fixes #13204]
load_missing_constant is a private method that basically plays the role of const_missing. This method has an error condition that is surprising: it raises if the class or module already has the missing constant. How is it possible that if the class of module has the constant Ruby has called const_missing in the first place? The answer is that the from_mod argument is self except for anonymous modules, because const_missing passes down Object in such case (see the comment in the source code of the patch for the rationale). But then, it is better to pass down Object *if Object is also missing the constant* and otherwise err with an informative message right away.
Diffstat (limited to 'activesupport')
-rw-r--r--activesupport/lib/active_support/dependencies.rb20
-rw-r--r--activesupport/test/dependencies_test.rb26
2 files changed, 22 insertions, 24 deletions
diff --git a/activesupport/lib/active_support/dependencies.rb b/activesupport/lib/active_support/dependencies.rb
index 19d4ff51d7..6be19771f5 100644
--- a/activesupport/lib/active_support/dependencies.rb
+++ b/activesupport/lib/active_support/dependencies.rb
@@ -176,14 +176,22 @@ module ActiveSupport #:nodoc:
end
def const_missing(const_name)
- # The interpreter does not pass nesting information, and in the
- # case of anonymous modules we cannot even make the trade-off of
- # assuming their name reflects the nesting. Resort to Object as
- # the only meaningful guess we can make.
- from_mod = anonymous? ? ::Object : self
+ from_mod = anonymous? ? guess_for_anonymous(const_name) : self
Dependencies.load_missing_constant(from_mod, const_name)
end
+ # Dependencies assumes the name of the module reflects the nesting (unless
+ # it can be proven that is not the case), and the path to the file that
+ # defines the constant. Anonymous modules cannot follow these conventions
+ # and we assume therefore the user wants to refer to a top-level constant.
+ def guess_for_anonymous(const_name)
+ if Object.const_defined?(const_name)
+ raise NameError, "#{const_name} cannot be autoloaded from an anonymous class or module"
+ else
+ Object
+ end
+ end
+
def unloadable(const_desc = self)
super(const_desc)
end
@@ -456,8 +464,6 @@ module ActiveSupport #:nodoc:
raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!"
end
- raise NameError, "#{from_mod} is not missing constant #{const_name}!" if from_mod.const_defined?(const_name, false)
-
qualified_name = qualified_name_for from_mod, const_name
path_suffix = qualified_name.underscore
diff --git a/activesupport/test/dependencies_test.rb b/activesupport/test/dependencies_test.rb
index 2392b71960..e56bab6d4c 100644
--- a/activesupport/test/dependencies_test.rb
+++ b/activesupport/test/dependencies_test.rb
@@ -530,29 +530,21 @@ class DependenciesTest < ActiveSupport::TestCase
end
end
- def test_const_missing_should_not_double_load
- $counting_loaded_times = 0
+ def test_const_missing_in_anonymous_modules_loads_top_level_constants
with_autoloading_fixtures do
- require_dependency '././counting_loader'
- assert_equal 1, $counting_loaded_times
- assert_raise(NameError) { ActiveSupport::Dependencies.load_missing_constant Object, :CountingLoader }
- assert_equal 1, $counting_loaded_times
+ # class_eval STRING pushes the class to the nesting of the eval'ed code.
+ klass = Class.new.class_eval "E"
+ assert_equal E, klass
end
end
- def test_const_missing_within_anonymous_module
- $counting_loaded_times = 0
- m = Module.new
- m.module_eval "def a() CountingLoader; end"
- extend m
+ def test_const_missing_in_anonymous_modules_raises_if_the_constant_belongs_to_Object
with_autoloading_fixtures do
- kls = nil
- assert_nothing_raised { kls = a }
- assert_equal "CountingLoader", kls.name
- assert_equal 1, $counting_loaded_times
+ require_dependency 'e'
- assert_nothing_raised { kls = a }
- assert_equal 1, $counting_loaded_times
+ mod = Module.new
+ msg = 'E cannot be autoloaded from an anonymous class or module'
+ assert_raise(NameError, msg) { mod::E }
end
end