[ruby-core:112802] [Ruby master Feature#19521] Support for `Module#name=` and `Class#name=`.
From:
"Eregon (Benoit Daloze) via ruby-core" <ruby-core@...>
Date:
2023-03-09 20:43:31 UTC
List:
ruby-core #112802
Issue #19521 has been updated by Eregon (Benoit Daloze).
ioquatix (Samuel Williams) wrote in #note-8:
> > It can lead to confusion and lies about the program state, e.g., pretend there is Foo::Bar when there isn't, even when remove_const/const_set are not used.
>
> As discussed, this is already the case, and can be easily replicated:
I just said: "even when remove_const/const_set are not used".
So sure it's possible with `remove_const` with a made-up example. Is it done in practice? I don't think so.
> I agree that the proposal makes it easier to fake class names, but that functionality is already possible and thus I don't see that as an issue being introduced by this proposal.
It makes it extremely easy to have fake names, in fact I would expect with this feature many people would do the mistake to use a constant-like name and so break the symmetry between module names and constant paths.
In the current situation, it's extremely rare `remove_const` is used and you would still have access to that module, e.g. I know of no gem doing that.
----------------------------------------
Feature #19521: Support for `Module#name=` and `Class#name=`.
https://bugs.ruby-lang.org/issues/19521#change-102304
* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
----------------------------------------
See https://bugs.ruby-lang.org/issues/19450 for previous discussion and motivation.
[This proposal](https://github.com/ruby/ruby/pull/7483) introduces `Module#name=` (and thus also `Class#name=`) to set the temporary class name. The name assignment has no effect if the module/class already has a permanent name.
```ruby
c = Class.new do
self.name = "fake name"
end
c = Class.new
c.name = "fake name"
```
Alternatively, we could use `set_name`:
```ruby
Class.new do
set_name "fake_name"
end
```
Setting the name of a class changes its current name, irrespective of whether it's been assigned a permanent name, or has nested modules/classes which have cached a previous name. We might like to limit the cases where a name is set, e.g. only once, only if the name is nil, or only if it's not already permanent. There is no real harm in any of those options, just inconsistency.
## Example usage
The current Ruby test suite has code which shows the usefulness of this new method:
```ruby
def labeled_module(name, &block)
Module.new do
singleton_class.class_eval {
define_method(:to_s) {name}
alias inspect to_s
alias name to_s
}
class_eval(&block) if block
end
end
module_function :labeled_module
def labeled_class(name, superclass = Object, &block)
Class.new(superclass) do
singleton_class.class_eval {
define_method(:to_s) {name}
alias inspect to_s
alias name to_s
}
class_eval(&block) if block
end
end
module_function :labeled_class
```
The updated code would look like this:
```ruby
def labeled_module(name, &block)
Module.new do
self.name = name
class_eval(&block) if block
end
end
def labeled_class(name, superclass = Object, &block)
Class.new(superclass) do
self.name = name
class_eval(&block) if block
end
end
module_function :labeled_class
```
Because the name cannot be set as part of `.new`, we have to have a separate block to set the name, before calling `class_eval`. I think the ergonomics and performance of this are slightly worse than the [counter proposal](https://bugs.ruby-lang.org/issues/19520).
--
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