Talk:VList: Difference between revisions
→Some problems
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::: Sure, but VList is meant to give persistent pointers. Realloc may move buffer and invalidate all pointers into its elements, while VList would not. --[[User:Ledrug|Ledrug]] 15:31, 13 September 2011 (UTC)
:::: But none of the task requirements mention pointers. And "persistent pointers" are a language-specific construct, as are "pointers". Also the advantages of pointers into an array over array indices are obscure, or negative, especially in the context of languages which implement some form of memory management. --[[User:Rdm|Rdm]] 15:40, 13 September 2011 (UTC)
::::: If your language provides higher level arrays and such, then all you need is a list, of course a data structure like VList would not be something you care -- but then you don't really worry about realloc either, do you? VList is a specifically low level construct, it ''is'' a way of doing memory management yourself. The sublist mentioned in the task is a use of the persistent pointer property: after you take an array slice, pushing more objects into the original list would not affect the validity of the slice, even though there's no further bookkeeping than just a pointer and an offset. --[[User:Ledrug|Ledrug]] 15:53, 13 September 2011 (UTC
:::::: Ok... perhaps this "languages with high level arrays do not need this" concept should be included in the task description? Meanwhile, to clone the array you need to copy the data from the first (biggest) block of data, which on average will contain c*n elements, where c is a constant (perhaps 0.25) and n is the length of the array. This means that that operation needs O(n) time. --[[User:Rdm|Rdm]] 16:25, 13 September 2011 (UTC)
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