# Code Review: HashEql **URL:** \ **Category:** IronRuby\ **Created:** [June 21, 2009, 5:39am UTC](https://www.ruby-forum.com/t/code-review-hasheql/170684 "2009-06-21T05:39:13Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![grujildo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/94ad74/32.png) [@grujildo](https://www.ruby-forum.com/u/grujildo)\ **Post date:** [June 21, 2009, 5:39am UTC](https://www.ruby-forum.com/t/code-review-hasheql/170684/1 "2009-06-21T05:39:13Z")
tfpt review “/shelveset:HashEql;REDMOND\tomat” Fixes implementation of Kernel#eql?, Kernel#==, Kernel#hash, Array#eql? and Array#hash and improves CLR interop. Improves performance of Array#- from quadratic algorithm to linear. CLR interop: “hash” is mapped to “GetHashCode” and following below rules: 1. ``` A Ruby call to Kernel#hash on a CLR object that overrides ``` GetHashCode will call that override. 1. ``` A Ruby call to Kernel#hash on a Ruby subclass of a CLR type will ``` call the GetHashCode of the CLR type if the Ruby subclass doesn’t implement “hash” method. 1. ``` A Ruby data structure (like Array) that calculates its hash code ``` based on hash codes of its items dynamically calls “hash” on those items. 1. ``` Any call from C# to GetHashCode on an instance of any Ruby class ``` will dynamically dispatch to either “hash”, “GetHashCode” or “get\_hash\_code” whichever is found first in standard method resolution order. If multiple of these methods are defined in the same class “hash” has highest priority and “get\_hash\_code” the lowest. This implies that a Ruby method definition with name “hash”, “GetHashCode” or “get\_hash\_code” in any Ruby class overrides GetHashCode of the parent CLR class. Similarly is “eql?” mapped to “Equals”. Kernel#== is an alias for “eql?” and hence has the same behavior when invoked (calls CLR Equals virtual method). However, 4) doesn’t hold for “==”, i.e. method == defined in a Ruby class does NOT override CLR Equals method. Adds /noadaptive option to unit test driver. Fixes removal of CLR methods. Simplifies implementation of IsRemovable on RubyMemberInfo using IsRubyMethod. IsRubyMethod returns true on all members that were defined by Ruby means, be it explicit method definition (def keyword), alias, alias\_method, define\_method, public/private/protected, overload, of, etc. CLR members used for definition of a new method (via define\_method, alias etc.) are called “detached” (as opposed to “attached” CLR members, which represent the original CLR members). They behave like any Ruby method with respect to method removal, virtual dispatch, IDO interop dispatch etc. So their IsRubyMethod implementation returns true. Tomas