2016-01-11 10:09 GMT+01:00 Sven Van Caekenberghe <sven@stfx.eu>:

David,

> On 11 Jan 2016, at 10:01, David Allouche <david@allouche.net> wrote:
>
> I happened to look at the new code for LayoutFrame>>#hash
>
> hash
>�� ^self species hash bitXor:
>�� (self leftFraction bitXor:
>�� (self leftOffset bitXor:
>�� (self topFraction bitXor:
>�� (self topOffset bitXor:
>�� (self rightFraction bitXor:
>�� (self rightOffset bitXor:
>�� (self bottomFraction bitXor:
>�� self bottomOffset)))))))
>
> This is a terrible, terrible way to compute a hash.
>
> 0 xor 0 = 1 xor 1 = 2 xor 2 = etc.
>
> NEVER compute hashes with xor, that's wrong, and it causes horrible, hard to debug, performance bugs down the road.

Yeah, that doesn't look very good ;-)

> SequenceableCollection>>#hash looks more like a correct way of doing it. I do not know what is the correct, efficient way to reuse this logic in LayoutFrame>>#hash.

There is actually a 2 part book just about hashing in Smalltalk:

http://www.lulu.com/shop/andres-valloud/hashing-in-smalltalk-theory-and-practice/paperback/product-3788892.html

It is said to be very good, I sadly have not yet read it ;-)

> By the way, how do you guys do code reviews for code integrated into the core?

'Pharo is yours' which means: if you encounter something odd, you are encouraged to improve it. Maybe first discuss it on the ML. If necessary create an issue. Better provide a fix.

Sven