ruby.git/test/ruby/test_frozen.rb, branch v4.0.2 The Ruby Programming Language Use actual class instead of singleton class in frozen error message 2025-12-09T22:35:50+00:00 Jeremy Evans code@jeremyevans.net 2025-11-23T03:51:46+00:00 76fb0d244b95a23116bfe72bb2422395c3a76477 With the following code: ```ruby object = [] object.singleton_class object.freeze object.instance_variable_set(:@a, 42) ``` The previous error message was: ``` can't modify frozen #<Class:#<Array:0x00000631d1308f78>>: [] ``` With this change, the error message is: ``` can't modify frozen Array: [] ``` Since we show the inspect value of the affected object, I think including the singleton class instead of the actual class if it exists makes the error message harder to understand. 
With the following code:

```ruby
object = []
object.singleton_class
object.freeze
object.instance_variable_set(:@a, 42)
```

The previous error message was:

```
can't modify frozen #<Class:#<Array:0x00000631d1308f78>>: []
```

With this change, the error message is:

```
can't modify frozen Array: []
```

Since we show the inspect value of the affected object, I think
including the singleton class instead of the actual class if it
exists makes the error message harder to understand.
Added tests for setting ivars on frozen objs 2022-06-16T15:48:08+00:00 Jemma Issroff jemmaissroff@gmail.com 2022-06-15T19:18:55+00:00 51835135a0586f439f581beece13df20100123f0