From: merch-redmine@...
Date: 2019-09-05T22:44:51+00:00
Subject: [ruby-core:94790] [Ruby master Bug#12984] `rescue *[]` should be equivalent to `rescue` as `method_call(*[])` is equivalent to `method_call`

Issue #12984 has been updated by jeremyevans0 (Jeremy Evans).

Assignee set to matz (Yukihiro Matsumoto)
Status changed from Feedback to Assigned

bughit (bug hit) wrote:
> I stopped getting email notifications from bugs.ruby-lang.org, to whom should I report this?

I'm not sure.

> I am going to reopen this because I did not have a chance to address your comment. And I made an argument that so far has not been addressed.

Your argument is basically that `rescue *[]` should mean `rescue`.  In reality, `rescue` is a shortcut for `rescue *[StandardError]`.  If you look at it from that perspective, it is obvious that `rescue *[]` and `rescue *[StandardError]` should not be the same thing.

> >  It should not mean rescue only exception classes in the array, unless the array is empty
> 
> That's not consistent with the meaning of splatting an empty array, whereas the opposite is.
> 
> In a construct that takes a coma separated list, splatting an empty array produces a void list (no values)
> 
> so `rescue *[Class1, Class2]` translates to `rescue Class1, Class2`
> `rescue *[Class1]` translates to `rescue Class1`
> and `rescue *[]` to a plain `rescue` which does not mean rescue nothing
> 
> That would be logical and consistent.
> 
> There is no explicit syntax for rescue nothing which would be something like `rescue()`, so `rescue *[]` has to mean `rescue` and not the non-existent `rescue()`

The explicit syntax for rescue nothing is `rescue *[]` :) .  As I showed in my earlier example, changing `rescue *array` to mean `rescue StandardError` if the array is empty will break backwards compatibility.

Assigning to matz to make a decision on this.

----------------------------------------
Bug #12984: `rescue *[]` should be equivalent to `rescue` as `method_call(*[])` is equivalent to `method_call`
https://bugs.ruby-lang.org/issues/12984#change-81406

* Author: bughit (bug hit)
* Status: Assigned
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* Target version: 
* ruby -v: ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-linux]
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
splatting an empty array to a construct that takes a list is suppose to be equivalent to specifying no list

```ruby
def foo
end

foo *[] #works

```

so `rescue *[]` should be equivalent to `rescue`

```ruby
begin
  raise 'error' #Uncaught exception
rescue *[]
  puts 'caught'
end
```




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