[ruby-core:55395] [ruby-trunk - Bug #8507] Keyword splat does not convert arg to Hash

Issue #8507 has been updated by stephencelis (Stephen Celis).


Is there logic behind the current state that I'm unaware of? Consistency is predictability, which is important when learning a new interface. If splatted nils are swallowed, why not double-splatted nils? One raising where the other doesn't surprised me.

With args, you can be sure that the value passed is an array when splatted out. Splatting itself is seen as a method of conversion for me and other Rubyists I've spoken with. The fact that double-splatting makes no attempt to convert the value seems to make it useless as a convention. What is the difference between the following method invocations?

def kwmethod **kwargs
  p kwargs
end

hash = { hello: 'world' }

kwmethod(hash)
kwmethod(**hash)

With *args, there is a clear reason to splat vs. not. Why not create a similar analog with keyword arguments?
----------------------------------------
Bug #8507: Keyword splat does not convert arg to Hash
https://bugs.ruby-lang.org/issues/8507#change-39819

Author: stephencelis (Stephen Celis)
Status: Feedback
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: syntax
Target version: current: 2.1.0
ruby -v: ruby 2.0.0p195 (2013-05-14 revision 40734) [x86_64-darwin12.3.0]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


A single splat is useful to convert an object to an array as it passes from one method to the next, so I expected the double-splat to do the same and convert the object to a hash.

<pre><code class="ruby">
def splat *args
  p args
end
def double_splat **kwargs
  p args
end
splat(*nil)  # []
splat(**nil) # TypeError: no implicit conversion of nil into Hash
</code></pre>

For the sake of consistency, wouldn't it make sense to wrap the double-splatted arg with Hash() the same way a single-splatted arg is wrapped with Array()?


-- 
http://bugs.ruby-lang.org/