From: merch-redmine@...
Date: 2015-10-22T16:45:30+00:00
Subject: [ruby-core:71160] [Ruby trunk - Feature #11537] Introduce "Safe	navigation operator"

Issue #11537 has been updated by Jeremy Evans.


Tom Reznick wrote:
> Hi,
> 
> I think we may have found some unexpected behavior with the `.?` operator.
> 
> If I call the following:
> 
>     s = Struct.new(:x)
>     o = s.new()
>     o.x #=> nil
>     o.x.nil? #=> true
>     o.x.?nil? #=> nil
>     o.x.kind_of?(NilClass) #=> true
>     o.x.?kind_of?(NilClass) #=> nil
>     o.x.methods.include?(:nil?) #=> true
> 
> 
> While it's arguably a bit peculiar to try to check that `nil` is `nil`, in a `nil`-safe way, `.?kind_of?(NilClass)` could reasonably return `true`.

I think it's completely expected that `nil.?kind_of?(NilClass)` returns `nil` and not `true`.  The whole point of `.?` is to return `nil` without calling the method if the receiver is `nil`.  I'm not sure if `.?` is a good idea syntax-wise, but if you are going to have it, it shouldn't have special cases for specific methods.

----------------------------------------
Feature #11537: Introduce "Safe navigation operator"
https://bugs.ruby-lang.org/issues/11537#change-54533

* Author: Hiroshi SHIBATA
* Status: Closed
* Priority: Normal
* Assignee: Yukihiro Matsumoto
----------------------------------------
I sometimes write following code with rails application:

```ruby
u = User.find(id)
if u && u.profile && u.profile.thumbnails && u.profiles.thumbnails.large
  ...
```

or

```ruby
# Use ActiveSupport
if u.try!(:profile).try!(:thumbnails).try!(:large)
 ...
```
I hope to write shortly above code. Groovy has above operator named "Safe navigation operator" with "`?.`" syntax.
Ruby can't use "`?.`" operator.

Can we use "`.?`" syntax. like this:

```ruby
u = User.find(id)
u.?profile.?thumbnails.?large
```

Matz. How do you think about this?




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