22 Jan
2023
22 Jan
'23
1:47 a.m.
Issue #19362 has been updated by nobu (Nobuyoshi Nakada).
While `String.allocate` and `Array.allocate` are defined, `Proc.allocate` is not.
What do you expect as the argument of `Proc#initialize_copy`?
----------------------------------------
Bug #19362: #dup on Proc doesn't call initialize_dup
https://bugs.ruby-lang.org/issues/19362#change-101394
* Author: zverok (Victor Shepelev)
* Status: Open
* Priority: Normal
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
In #17545, `#dup` had changed to create an instance of the subclass.
It, though, doesn't invoke `initialize_dup` of the subclass, unlike other standard
classes.
```ruby
class MyAry < Array
def initialize_dup(...)
p(self.class, ...)
super
end
end
class MyString < String
def initialize_dup(...)
p(self.class, ...)
super
end
end
class MyProc < Proc
def initialize_dup(...)
p(self.class, ...)
super
end
end
MyString.new('test').dup # prints MyString, "test"
MyAry.new(['test']).dup # prints MyAry, ["test"]
MyProc.new { 'test' }.dup # doesn't print anything
```
This makes the change in #17545 useless: while inheriting from core classes is indeed
marginal, one of author's intention might be carrying additional information with the
Proc instance, and bypassing `#initialize_dup` makes it impossible to maintain this
information.
It seems that actually `#initialize_dup` is also invoked on the core classes themselves,
but ignored on `Proc`.
```ruby
class Array
def initialize_dup(...)
p(self.class, ...)
super
end
end
class String
def initialize_dup(...)
p(self.class, ...)
super
end
end
class Proc
def initialize_dup(...)
p(self.class, ...)
super
end
end
'test'.dup # prints String, "test"
['test'].dup # prints Array, ["test"]
Proc.new { 'test' }.dup # doesn't print anything
```
Which is an even more marginal problem but still an inconsistency.
--
https://bugs.ruby-lang.org/