#16137: lazy_list from various input data
-------------------------------------+-------------------------------------
Reporter: MatthieuDien | Owner:
Type: enhancement | Status: new
Priority: major | Milestone: sage-6.4
Component: misc | Resolution:
Keywords: LazyPowerSeries, | Merged in:
lazy_list, days57 | Reviewers:
Authors: Vincent | Work issues:
Delecroix, Matthieu Dien | Commit:
Report Upstream: N/A | 37e67683e7a2f10152ba3a01b8aed508fe92f0f1
Branch: | Stopgaps:
u/MatthieuDien/lazy_list_from_various_input_data|
Dependencies: |
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Comment (by vdelecroix):
Hello,
Cool. Thanks Matthieu!
1) Please use complete names `lazy_list_from_function` and not
abreviations. (see also item 3 of Martin)
2) For your specifications, I really do not think it is the best way to
do. Very often you have functions that update *many* values at a time
(think about Newton method, or substitutively defined sequences). I would
prefer much more `lazy_list_from_function` whose argument would be a
function `f(computed_values)` and which would update the list
`computed_values` with one iteration of the algorithm (and return nothing
or possibly an error code). And it has no sense to send the size of the
cache to that function (since it is a list and a list knows its length).
3) I think we need more classes (I am not convinced by all names). Some of
them might be implemented in further tickets
{{{
lazy_list: abstract class
|
+-- lazy_list_periodic: ultimately periodic lazy list (attributes=two
lists)
|
+-- lazy_list_explicit: (attribute=function n-> u_n)
|
+-- lazy_list_concatenation: a concatenation of a finite liste and a lazy
list
|
+-- lazy_list_slice: a slice of another lazy list
|
+-- lazy_list_with_cache: a cache management
|
+-- lazy_list_from_iterator: the old lazy_list
|
+-- lazy_list_from_function: update function (basically what you
did)
}}}
4) we need a unique entry point for all these classes which must be of
course `lazy_list`.
5) In the old implementation `lazy_list` were immutable. It has the
advantage of having shared slices. On the other hand it is annoying
because they are immutable and hence it will be forbidden to have
operations like "f += 1" without a (light) copy.
Vincent
--
Ticket URL: <http://trac.sagemath.org/ticket/16137#comment:24>
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