On 01 Aug 2014, at 3:20 , Serge Stinckwich <serge.stinckwich@gmail.com> wrote:

Dear all,

using Sci-Smalltalk, we found with Natalia that sometimes blocks have
strange behavior :
https://groups.google.com/forum/#!topic/scismalltalk/HmGpTkzLOdQ

I was able to create a more simpler example using only Pharo.
If you try, the following expression, there is no problem:

|state values |
values := (1 to: 10000) collect: [ : t| state := { t. t+1. t+2.}].
(1 to: 10000) do:[:i | (values at:i) at:2].

and you do more iterations, an error appears (Instances of
SmallInteger are not indexable),
because from time to time, an array is replaced by an integer:

|state values |
values := (1 to: 100000) collect: [ : t| state := { t. t+1. t+2.}].
(1 to: 100000) do:[:i | (values at:i) at:2].

and if you move the state variable inside the block, it works again :

| values |
values := (1 to: 100000) collect: [ : t| |state| state := { t. t+1. t+2.}].
(1 to: 100000) do:[:i | (values at:i) at:2].

Same problem in Pharo 3.0 or Pharo 4.0

Regards,

Speaking of which, when trying to inspect the array, it���s incredibly slow���

The main reason for this?

BasicIndexedEyeElement >> hash

^super hash bitXor: index hash

The super implementation?

AbstractEyeElement >> hash

^host hash

Guess what the host of an indexedEyeElement is? That���s right, the collection���

So every time it tries to find the cached icon of a line (which is, 10-20 times per refresh cycle depending on the view), it iterates through the 100000 element array to calculate its hash���

I���d recommend either removing the super call from BasicIndexedEyeElement, or tell the AbstractEyeElement to use the identityHash of its host instead.

Bonus: It also invokes a #DNU hander every time, since DictionaryValueHolder >> at:ifAbsentPut: is implemented

self at: key ifAbsent: [].

instead of��

value at: key ifAbsent: [].

Code quality progress. Yay.

Cheers,

Henry