On Fri, Feb 3, 2012 at 6:18 AM, Lukas Renggli renggli@gmail.com wrote:
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.
The problems are that the primitive is defined to be destructive, and code could be depending on the destructive update behaviour. Would it be feasible to use a new primitive that did the right thing in the case of overlap, or do you definitely want to change primitive 105?
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):
- forward: #do:, #collect:, #select:, #detect:, #inject:into:, ...
- 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
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.
The problems are that the primitive is defined to be destructive, and code could be depending on the destructive update behaviour. Would it be feasible to use a new primitive that did the right thing in the case of overlap, or do you definitely want to change primitive 105?
A new primitive would be prefect. Like this we can even have a nice fallback in case the VM doesn't have the primitive yet.
Lukas
vm-dev@lists.squeakfoundation.org
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Eliot Miranda -
Lukas Renggli