[ruby-core:94198] [Ruby master Bug#16086] OpenStruct method access with a block does not raise

From: nobu@...
Date: 2019-08-08 13:22:38 UTC
List: ruby-core #94198
Issue #16086 has been updated by nobu (Nobuyoshi Nakada).

Status changed from Open to Feedback

kke (Kimmo Lehto) wrote:
> This can cause confusion.
> 
> ```ruby
>   > OpenStruct.new(hello: 'world').each { |k, v| puts k.upcase } # there's no "each" method
>   => nil
>   > OpenStruct.new(hello: 'world').eahc_pair { |k, v| puts k.upcase } # each_pair typo
>   => nil
>   ```
> 
> An undefined key with a block should maybe raise `NoMethodError` or `ArgumentError`?

That is `OpenStruct`, undefined key does not raise an exception.
And unused block is silently ignored in common.

> A defined key with a block seems to yield the value, I don't see this being documented:
> 
> ```ruby
>   > OpenStruct.new(hello: 'world').hello { |k| puts k.upcase } 
>   HELLO
> ```
> 
> Maybe it should raise `ArgumentError` too?

I haven't seen such behavior.
```
$ ruby -rostruct -e 'p OpenStruct.new(hello: "world").hello { |k| puts k.upcase }'
"world"
```



----------------------------------------
Bug #16086: OpenStruct method access with a block does not raise
https://bugs.ruby-lang.org/issues/16086#change-80493

* Author: kke (Kimmo Lehto)
* Status: Feedback
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
This can cause confusion.

```ruby
  > OpenStruct.new(hello: 'world').each { |k, v| puts k.upcase } # there's no "each" method
  => nil
  > OpenStruct.new(hello: 'world').eahc_pair { |k, v| puts k.upcase } # each_pair typo
  => nil
  ```

An undefined key with a block should maybe raise `NoMethodError` or `ArgumentError`?

A defined key with a block seems to yield the value, I don't see this being documented:

```ruby
  > OpenStruct.new(hello: 'world').hello { |k| puts k.upcase } 
  HELLO
```

Maybe it should raise `ArgumentError` too?

Related: https://bugs.ruby-lang.org/issues/15515




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