From: Sylvain Joyeux <sylvain.joyeux@13robotics.com>
Date: 2016-09-13T13:57:31-03:00
Subject: [ruby-core:77262] RFC: optimizations opportunities in Hash#merge!

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Hello everyone.

I'm using Hash#merge and other hash-related update methods extensively, to
the point where I spend a significant amount of time in #hash.

So I went digging. It appears that Hash#merge is actually re-hashing its
keys twice (once to compare the two hashes, and once to re-assign to the
receiver).

However, under the assumption that the block in Hash#merge! is not allowed
to modify the key, no hashing should be needed at all.

Or am I missing something ?

I am ready to work on this, but I want to have a feel for whether such work
would be welcome by the code devs before I invest time in it ... rather
than have it thrown away as WONTFIX later.

Regards,
Sylvain

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<div dir=3D"ltr">Hello everyone.<div><br></div><div>I&#39;m using Hash#merg=
e and other hash-related update methods extensively, to the point where I s=
pend a significant amount of time in #hash.</div><div><br></div><div>So I w=
ent digging. It appears that Hash#merge is actually re-hashing its keys twi=
ce (once to compare the two hashes, and once to re-assign to the receiver).=
</div><div><br></div><div>However, under the assumption that the block in H=
ash#merge! is not allowed to modify the key, no hashing should be needed at=
 all.</div><div><br></div><div>Or am I missing something ?</div><div><br></=
div><div>I am ready to work on this, but I want to have a feel for whether =
such work would be welcome by the code devs before I invest time in it ... =
rather than have it thrown away as WONTFIX later.</div><div><br></div><div>=
Regards,</div><div>Sylvain</div></div>

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