[ruby-core:68595] [Ruby trunk - Feature #10984] Hash#contain? to check whether hash contains other hash

Issue #10984 has been updated by Robert A. Heiler.


I have no particular pro or contra opinion. I merely wish to think that #include? is a better name because Array also has include? and
String also has include?. While a Hash#include? may not be exactly the same as the other two #includes?, I think the name would be
ok. #contain? feels a bit weird, I mean you could use Array#contain? too (on the other hand, you could use an alias just as .map
vs. .collect; I myself use solely .map, other people can use .collect, things are fine) ok so bottom line from me, I think
Hash#include? is a perfectly suitable name for it too as Erik wrote. Perhaps for Ruby 3.0

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Feature #10984: Hash#contain? to check whether hash contains other hash
https://bugs.ruby-lang.org/issues/10984#change-51907

* Author: Olivier Lacan
* Status: Open
* Priority: Normal
* Assignee: 
----------------------------------------
Comparing hashes seems like a common practice but there currently isn't a method to ask a 
hash instance whether it includes another hash instance.

The most intuitive method to reach for would be `Hash#include?` but it is in fact an alias to `Hash#has_key?`

What I'm looking for can be achieved with:

~~~
class Hash
  def contain?(other)
    self.merge(other) == self
  end
end
~~~

Here's a simple demo of `#contain?` in use:

~~~
{ a: true, b: false }.contain?({ a: true})
# => true

{ a: true, b: false }.contain?({ b: false})
# => true

{ a: true, b: false }.contain?({ a: false})
# => false

{ a: true, b: false }.contain?({ c: true})
# => false
~~~

One important note is that this method is *not checking for nested hash matches*.
This may need to be addressed when the parameters include a nested hash perhaps.

Thanks to Terence Lee's help, nobu created a patch for this feature last year. 
I've only modified the name of the method from [his original patch](https://gist.github.com/nobu/dfe8ba14a48fc949f2ed) and attached it to this issue.

---Files--------------------------------
Hash#contain_.patch (2.22 KB)


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