Issue #10845 has been updated by Eregon (Benoit Daloze).


@ioquatix See #6087. Returning subclass instances leads to all kind of issues, because there is no good way to build the subclass instance.

+1 to do it for String since we did for Array.

Maybe we should do it for Hash too?
It seems already the case for most Hash methods but not all (e.g. `Hash#merge`).

----------------------------------------
Bug #10845: Subclassing String
https://bugs.ruby-lang.org/issues/10845#change-88639

* Author: sawa (Tsuyoshi Sawada)
* Status: Open
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* ruby -v: 2.2
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
If I make a subclass of `String`, the method `*` returns an instance of that class.

~~~ruby
class MyString < String
end

MyString.new("foo").*(2).class #=> MyString
~~~

This is different from other similar operations like `+` and `%`, which return a `String` instance.

~~~ruby
MyString.new("foo").+("bar").class #=> String
MyString.new("%{foo}").%(foo: "bar").class #=> String
~~~

I don't see clear reason why `*` is to be different from `+` and `%`, and thought that perhaps either the behaviour with `*` is a bug, or the behaviour with `+` and `%` is a bug.

Or, is a reason why they are different?



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