[ruby-core:93407] [Ruby trunk Bug#15708] Implicit numbered argument decomposes an array
From:
eregontp@...
Date:
2019-06-28 10:53:56 UTC
List:
ruby-core #93407
Issue #15708 has been updated by Eregon (Benoit Daloze).
Assignee set to matz (Yukihiro Matsumoto)
Status changed from Rejected to Assigned
IMHO, this is very much a bug, and the single reason I heard for it seems largely outweigh by being non-intuitive and breaking code.
@nobu BTW, that reason has not been written here yet and should be, please write it down.
IMHO using @N will always be surprising for debugging since it changes arity.
So I reopen this and assign to matz.
I believe we all agree that if we accept only a single unnamed parameter, that it should be the same as `{ |x| }`.
I don't think that rule should change with multiple unnamed parameters.
TBH, I don't think this behavior is rational language design (taking the semantics of a almost-never-used syntax (because it's dangerous) for a new syntactic sugar), but it's just my opinion.
----------------------------------------
Bug #15708: Implicit numbered argument decomposes an array
https://bugs.ruby-lang.org/issues/15708#change-78948
* Author: sawa (Tsuyoshi Sawada)
* Status: Assigned
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* Target version:
* ruby -v: 2.7.0dev
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
In the following, `@1` refers to the entire item iterated:
```ruby
a = [1, 2, 3]
a.map{|x| x} # => [1, 2, 3]
a.map{@1} # => [1, 2, 3]
```
whereas in the following, `@1` refers to the first item achieved by decomposing the item iterated, behaving the same as `x` given by `|(x)|` rather than by `|x|`:
```ruby
a = [[1], [2], [3]]
a.map{|x| x} # => [[1], [2], [3]]
a.map{|(x)| x} # => [1, 2, 3]
a.map{@1} # => [1, 2, 3]
```
Is this intended?
---Files--------------------------------
single-implicit-arg-no-destructure.diff (471 Bytes)
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