[ruby-core:96508] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters

[ruby-core:96508] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters

[aaronc20000]

Issue #16456 has been reported by aaronc81 (Aaron Christiansen).

----------------------------------------
Feature #16456: Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters
https://bugs.ruby-lang.org/issues/16456

* Author: aaronc81 (Aaron Christiansen)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
A method defined with `...` as its parameter list is equivalent to one defined with `*args, &blk`, according to `Method#parameters`.

```
def foo(...); end
p method(:foo).parameters
# => [[:rest, :*], [:block, :&]]
```

Even in Ruby 2.7, `...` and `*args, &blk` are not _quite_ equivalent as the latter may produce a warning where the former does not. In Ruby 3.0 and beyond, `...` and `*args, &blk` will have a substantial semantic difference. Due to this, I don't consider the current behaviour of `Method#parameters` particularly ideal when dealing with methods using this new syntax.

If the goal of `...` is to be a "delegate everything" operator, even when parameter passing is changed like in Ruby 3.0, I would propose that `Method#parameters` considers it a unique type of parameter. For example:

```
def foo(...); end
p method(:foo).parameters
# => [[:delegate, :"..."]]
```



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

[ruby-core:96511] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters

[eregontp]

Issue #16456 has been updated by Eregon (Benoit Daloze).


I think it should be:
```ruby
[[:rest, :*], [:keyrest, :**], [:block, :&]]
```

because that's what it will act like in Ruby 3.0+.

Is there an advantage to have its own type of parameter?
That would make usages of `#parameters` more complex for I think very little gain.


----------------------------------------
Feature #16456: Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters
https://bugs.ruby-lang.org/issues/16456#change-83444

* Author: aaronc81 (Aaron Christiansen)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
A method defined with `...` as its parameter list is equivalent to one defined with `*args, &blk`, according to `Method#parameters`.

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:rest, :*], [:block, :&]]
```

Even in Ruby 2.7, `...` and `*args, &blk` are not *quite* equivalent as the latter may produce a warning where the former does not. In Ruby 3.0 and beyond, `...` and `*args, &blk` will have a substantial semantic difference. Due to this, I don't consider the current behaviour of `Method#parameters` particularly ideal when dealing with methods using this new syntax.

If the goal of `...` is to be a "delegate everything" operator, even when parameter passing is changed like in Ruby 3.0, I would propose that `Method#parameters` considers it a unique type of parameter. For example:

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:delegate, :"..."]]
```



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

[ruby-core:96513] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters

[zverok.offline]

Issue #16456 has been updated by zverok (Victor Shepelev).


> I think it should be:

```ruby
[[:rest, :*], [:keyrest, :**], [:block, :&]]
```
(I have a deja vu we already discussed it :)))

Names are redundant, it should be just
```ruby
[[:rest], [:keyrest], [:block]]
```

Like this:

```ruby
def foo(*, **, &b)
end

p method(:foo).parameters
# => [[:rest], [:keyrest], [:block, :b]]
```

(Not sure about "block" parameter -- unnamed block parameters aren't existing in current Ruby)

----------------------------------------
Feature #16456: Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters
https://bugs.ruby-lang.org/issues/16456#change-83445

* Author: aaronc81 (Aaron Christiansen)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
A method defined with `...` as its parameter list is equivalent to one defined with `*args, &blk`, according to `Method#parameters`.

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:rest, :*], [:block, :&]]
```

Even in Ruby 2.7, `...` and `*args, &blk` are not *quite* equivalent as the latter may produce a warning where the former does not. In Ruby 3.0 and beyond, `...` and `*args, &blk` will have a substantial semantic difference. Due to this, I don't consider the current behaviour of `Method#parameters` particularly ideal when dealing with methods using this new syntax.

If the goal of `...` is to be a "delegate everything" operator, even when parameter passing is changed like in Ruby 3.0, I would propose that `Method#parameters` considers it a unique type of parameter. For example:

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:delegate, :"..."]]
```



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

[ruby-core:96517] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters

[aaronc20000]

Issue #16456 has been updated by aaronc81 (Aaron Christiansen).


> Is there an advantage to have its own type of parameter?

I believe the advantages of doing this are:

  - If Ruby ever introduces a new type of parameter, the result of `#parameters` won't need to change for existing code which uses `...`, making upgrades easier. This is especially important if `...` is designed as a future-proof way of delegation, as then it seems important that its behaviour shouldn't change between versions.
  - It could be useful for introspection to be able to differentiate between the two. For example, this could allow a complex DSL to assign a special meaning to `...`.

----------------------------------------
Feature #16456: Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters
https://bugs.ruby-lang.org/issues/16456#change-83449

* Author: aaronc81 (Aaron Christiansen)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
A method defined with `...` as its parameter list is equivalent to one defined with `*args, &blk`, according to `Method#parameters`.

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:rest, :*], [:block, :&]]
```

Even in Ruby 2.7, `...` and `*args, &blk` are not *quite* equivalent as the latter may produce a warning where the former does not. In Ruby 3.0 and beyond, `...` and `*args, &blk` will have a substantial semantic difference. Due to this, I don't consider the current behaviour of `Method#parameters` particularly ideal when dealing with methods using this new syntax.

If the goal of `...` is to be a "delegate everything" operator, even when parameter passing is changed like in Ruby 3.0, I would propose that `Method#parameters` considers it a unique type of parameter. For example:

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:delegate, :"..."]]
```



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

[ruby-core:96585] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters

[daniel]

Issue #16456 has been updated by Dan0042 (Daniel DeLorme).


In the future it will be possible to combine `...` with other arguments. So if we think about what `parameters` would return in cases like these...

```ruby
method(def foo(a, *args, ...); end).parameters
#1=> [[:req, :a], [:rest, :args], [:delegate]]
#2=> [[:req, :a], [:rest, :args], [:keyrest], [:block]]
#3=> [[:req, :a], [:rest, :args], [:rest], [:keyrest], [:block]]

method(def foo(a, **kw, ...); end).parameters
#1=> [[:req, :a], [:keyrest, :kw], [:delegate]]
#2=> [[:req, :a], [:keyrest, :kw], [:rest], [:block]]
#3=> [[:req, :a], [:keyrest, :kw], [:rest], [:keyrest], [:block]]
```

I see the point of wanting to know if the method signature includes `...` or not, but I don't think I like the idea of having a `:delegate` that can mean different things.

What about this?
`[[:rest, :"..."], [:keyrest, :"..."], [:block, :"..."]]`

----------------------------------------
Feature #16456: Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters
https://bugs.ruby-lang.org/issues/16456#change-83552

* Author: aaronc81 (Aaron Christiansen)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
A method defined with `...` as its parameter list is equivalent to one defined with `*args, &blk`, according to `Method#parameters`.

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:rest, :*], [:block, :&]]
```

Even in Ruby 2.7, `...` and `*args, &blk` are not *quite* equivalent as the latter may produce a warning where the former does not. In Ruby 3.0 and beyond, `...` and `*args, &blk` will have a substantial semantic difference. Due to this, I don't consider the current behaviour of `Method#parameters` particularly ideal when dealing with methods using this new syntax.

If the goal of `...` is to be a "delegate everything" operator, even when parameter passing is changed like in Ruby 3.0, I would propose that `Method#parameters` considers it a unique type of parameter. For example:

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:delegate, :"..."]]
```



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

[ruby-core:96608] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters

[aaronc20000]

Issue #16456 has been updated by aaronc81 (Aaron Christiansen).


I think that the `[[:rest, :"..."], [:keyrest, :"..."], [:block, :"..."]]` solution looks like a good option, as it keeps roughly the same behaviour while adding the differentiation between `*args, &blk` and `...`.

----------------------------------------
Feature #16456: Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters
https://bugs.ruby-lang.org/issues/16456#change-83578

* Author: aaronc81 (Aaron Christiansen)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
A method defined with `...` as its parameter list is equivalent to one defined with `*args, &blk`, according to `Method#parameters`.

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:rest, :*], [:block, :&]]
```

Even in Ruby 2.7, `...` and `*args, &blk` are not *quite* equivalent as the latter may produce a warning where the former does not. In Ruby 3.0 and beyond, `...` and `*args, &blk` will have a substantial semantic difference. Due to this, I don't consider the current behaviour of `Method#parameters` particularly ideal when dealing with methods using this new syntax.

If the goal of `...` is to be a "delegate everything" operator, even when parameter passing is changed like in Ruby 3.0, I would propose that `Method#parameters` considers it a unique type of parameter. For example:

```ruby
def foo(...); end
p method(:foo).parameters
# => [[:delegate, :"..."]]
```



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