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Date: Wed, 17 Dec 2014 17:05:20 -0700
Message-ID: <CAFMT4NpneUuE_mWA62HumktuUYCM6Sv-z7L_amSdrfV5emZiQA@mail.gmail.com>
To: Stanislav Malyshev <smalyshev@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [PHP-DEV] [RFC][VOTE] Objects as Keys
From: levim@php.net (Levi Morrison)

>> Programmable hashes of objects should be external to the object anyway
>> because eventually someone wants to store the same object in a
>> different way in two different structures.
>
> That is the requirement that no language I can think of implements -
> Java, Python, Ruby, C# all have programmatic hash method, and none of
> them changes it for different structures.

C++ commonly does this. You pass a "hash function" as a template or
constructor argument and use that for the structure. Additionally,
this allows you to easily support types that don't natively provide
internal hashing functions (such as objects from a third party
library).

In this case, doing it like Java, C# et al is an example of most
languages getting it wrong, not them getting it right.