Re: [Pharo-project] About linkedlist

>>>> what is the diff between arrayList and vectorList ?
>>>
>>> ArrayList is double ended (very much like OrderedCollection),
>>> VectorList is single ended. I was just experimenting to see if it
>>> makes a difference.
>
> ok. I like to see such kind of experiment.
> Was the name based on something that people use?

No, it is a randomly chosen and meaningless name. I guess in the end
there will only be one named ArrayList, but I am not sure which
implementation is better.

Just a note to the VM developers: The primitive
Array>>#replaceFrom:to:with:startingAt: is absolutely central to the
implementation of efficient collections. While it works well if you
copy from one array to the other, it is broken if source and
destination array are the same and the areas overlap. Would it be
possible to fix this. Even "memmove(void*, void*, size_t)" in C can
handle this situation correctly.

>>>> Do you have some kind of high level description of Container explaining the rationale, ideas and approach.
>>>
>>> The core idea is to split iteration from containment; I think a
>>> horrible design mistake in the Smalltalk-80 collections.
>
> I thought about that when I read the Iterator.
> I would not say that this is horrible. I think that for default case this is not that bad.
> Now when you want to navigate a large graph and control the navigation then you should have an iterator.

I think it is pretty horrible. I can think of at least 4 meaningful
ways to iterate over an simple array (for other collections there are
even more ways):

   1. forward: #do:, #collect:, #select:, #detect:, #inject:into:, ...
   2. forward with index: #keysAndValuesDo:, #collectWithIndex:,
everything else is not possible
   3. backward: #reverseDo:, everything else is not possible
   4. backward with index: not possible

If you split the iterator into a separate object, suddenly all of this
becomes trivial. A #collect: remains a #collect: no matter if you are
going forward or backward, or with or without index.

Lukas

--
Lukas Renggli
www.lukas-renggli.ch