[ruby-core:93734] [Ruby master Bug#8743] Inconsistent behaviour calling public_methods on class (Plus documentation slightly ambiguous)

[ruby-core:93734] [Ruby master Bug#8743] Inconsistent behaviour calling public_methods on class (Plus documentation slightly ambiguous)

[merch-redmine]

Issue #8743 has been updated by jeremyevans0 (Jeremy Evans).

Backport deleted (1.9.3: UNKNOWN, 2.0.0: UNKNOWN)
Status changed from Open to Closed

The reason for this interesting behavior is because the documentation for include flag (2nd argument) for `public_methods` is not precise.  It states:

```
If the all parameter is set to false, only those methods
in the receiver will be listed.
```

However, the behavior is actually:

```
If the all parameter is set to false, the list will include methods
in ancestors, stopping after a non-singleton class is encountered
(including the methods from the non-singleton class).
```

The lookup process for `Empty.public_methods(false)` is something like this:

* Empty.singleton_class # adds no methods
* Object.singleton_class # adds no methods
* BasicObject.singleton_class # adds no methods
* Class # adds 3 methods `[:allocate, :superclass, :new]`
* Module # does not get here, as Class is not a singleton class

So that is the reason `Empty.public_methods(false)` gives you `[:allocate, :superclass, :new]`.

`B.public_methods(false)` including singleton methods from `A` is similar:

* B.singleton_class # adds no methods
* A.singleton_class # adds 1 method `[:bar]`
* Object.singleton_class # adds no methods
* BasicObject.singleton_class # adds no methods
* Class # adds 3 methods `[:allocate, :superclass, :new]`
* Module # does not get here, as Class is not a singleton class

Which is the reason that `Bar.public_methods(false)` gives you `[:bar, :allocate, :superclass, :new]`.

I'm not sure it worth updating the documentation to be more precise in this area, but I'm open to suggestions. 

----------------------------------------
Bug #8743: Inconsistent behaviour calling public_methods on class (Plus documentation slightly ambiguous)
https://bugs.ruby-lang.org/issues/8743#change-79371

* Author: stestagg (Steve Stagg)
* Status: Closed
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.1.0dev (2013-08-06 trunk 42401) [x86_64-darwin12.4.0]
* Backport: 
----------------------------------------
=begin
= Background

I was trying to identify classes on which a specific class method (def self.xx) was actually defined (in the case of multiple levels of inheritance).  This currently doesn't seem to be possible, although the docs suggest that calling class.public_methods(false) should do this.

While investigating, I discovered that the behaviour of calling instance.public_methods(false) is not consistent with that of calling class.public_methods(false) [They should be different, of course, but the behaviour should be consistent].  The attached test script highlights this.

= Steps to Reproduce

Run the attached ruby script

= Expected Result

Ideally, all tests pass, but at `least test_consistent_behaviour` should pass

= Actual Results

test_this_is_what_i_expect, and test_consistent_behaviour both fail.

= Example test output

 steves@sapphire ~/s/t/ruby> env RUBYLIB=./lib ./ruby ~/foo.rb
 Run options:
 
 # Running tests:
 
 [2/5] PublicMethodsTest#test_consistent_behaviour = 0.00 s
 1) Failure:
 PublicMethodsTest#test_consistent_behaviour [/Users/steves/foo.rb:73]:
 Differences: bar. "bar" is inherited from A, but doesn't include methods inherited from Object!
 
 [5/5] PublicMethodsTest#test_this_is_what_i_expect = 0.00 s
 2) Failure:
 PublicMethodsTest#test_this_is_what_i_expect [/Users/steves/foo.rb:59]:
 Differences: allocate, new, superclass.
 
 Finished tests in 0.005998s, 833.6112 tests/s, 2834.2781 assertions/s.
 5 tests, 17 assertions, 2 failures, 0 errors, 0 skips
 
 ruby -v: ruby 2.1.0dev (2013-08-06 trunk 42401) [x86_64-darwin12.4.0]

Seen on ruby 1.8, 2.0 and trunk
=end


---Files--------------------------------
foo.rb (2.22 KB)


-- 
https://bugs.ruby-lang.org/