From: prijutme4ty@... Date: 2015-11-19T01:38:07+00:00 Subject: [ruby-core:71569] [Ruby trunk - Bug #10984] Hash#contain? to check whether hash contains other hash Issue #10984 has been updated by Ilya Vorontsov. Tracker changed from Feature to Bug > Akira Tanaka wrote: > > ``` > % ruby -e ' > class Hash > def <=(other) > self.merge(other) == other > end > def >=(other) > self.merge(other) == self > end > def <(other) > self <= other && self != other > end > def >(other) > self >= other && self != other > end > end > ``` This implies that ```ruby {a: 1, b: 2} <= {a: 1, b: 3} {a: 1, b: 3} <= {a: 1, b: 2} ``` Is that expected? This breaks the main use-case in testing method results. ---------------------------------------- Bug #10984: Hash#contain? to check whether hash contains other hash https://bugs.ruby-lang.org/issues/10984#change-54949 * Author: Olivier Lacan * Status: Closed * Priority: Normal * Assignee: Akira Tanaka * ruby -v: * Backport: ---------------------------------------- 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) -- https://bugs.ruby-lang.org/