From: grzegorz.bizon@...
Date: 2015-04-14T06:51:17+00:00
Subject: [ruby-core:68886] [Ruby trunk - Feature #11034] Nil Conditional

Issue #11034 has been updated by Grzegorz Bizon.


Hi again !

I've made new attempt to create nil conditional operator (https://github.com/nil-conditional). This is Ruby implementation, you can check it out here: https://github.com/grzesiek/nil-conditional/blob/master/lib/nil_conditional.rb.

It is simple, it encapsulates objects in NilConditional instance. Sample usage:

~~~
def nil_test(str)
  str._?.concat("456")
end

nil_test("123")
=> "123456"

nil_test(nil)
=> #<NilConditional:0x007fc602016718 @object=nil>

nil_test(nil).nil?
=> true
~~~

What do you think about that ? It seems (for me) that this is sufficient, and native implementation is not necessary with this approach.

Anyway, thanks for feedback !

Kind regards,
 Grzegorz

----------------------------------------
Feature #11034: Nil Conditional
https://bugs.ruby-lang.org/issues/11034#change-52155

* Author: Grzegorz Bizon
* Status: Open
* Priority: Normal
* Assignee: 
----------------------------------------
Hi everyone !

Some time ago I was thinking about Nil Conditional Operator in Ruby (`??`). This would be particularly useful to avoid frequent checking for nil, and should behave and look like Null Conditional Operator introduced in C# 6.0.

I was thinking about something like this (assume `var` is nil or doesn't exist):

~~~ruby
var??.method1.method2(123, 345).method3 { |i| i == 1 }
=> nil
~~~

When `var` is nil or doesn't exist, code above should return nil or NilConditionalClass object instead of raising NoMethodError or NameError.
This can also work with methods (assume `var` exists):

~~~ruby
var.method1??.method2(a, b)
=> nil
~~~

When `var` exists and can receive `method1`, but `method1` returns nil - this shouldn return nil instead of raising  `NoMethodError: undefined method `method2' for nil:NilClass`

When `var` exists and is not nil, and can receive `method1`, and object returned by `method1` can receive `method2` this, of course should behave as expected (like version without `??` operator) and return value according to implementation of method2.

When `var` doesn't exist - this should raise NameError.


I tried to create gem for that (https://github.com/grzesiek/nil-conditional) but from now on, only native implementation seems reasonable.

What do you think about that feature ? Maybe it is already considered, but I couldn't find anything similar at Google/this issue tracker (in that case I'm sorry for duplicate).

Thanks in advance for feedback !

Kind regards,
 Grzegorz




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