Fix concat_type_lists_unique_t to be "more unique" #546
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The current behavior of concat_type_lists_unique_t is a little
confusing.
```
concat_type_lists_unique_t<type_list<int, int>, type_list<int>> ->
type_list<int, int>
concat_type_lists_unique_t<type_list<int>, type_list<int, int>> ->
type_list<int>
```
In other words, concat_type_lists_unique_t is not commutative.
The docs seemed to indicate concat_type_lists_unique_t expected the
lists to already contain unique elements (the comment seemed incomplete
though). I am changing the behavior of concat_type_lists_unique_t
to remove duplicate elements from the input lists, since it
conveniently fixes any sender algos that use it to construct the
value_types of the output sender to not contain duplicate types.
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ccotter
commented
Jun 26, 2023
| }); | ||
| static_assert(std::is_same_v< | ||
| decltype(s)::value_types<std::variant, std::tuple>, | ||
| std::variant<std::tuple<double>, std::tuple<int>> |
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My main goal of this PR was to fix the output sender from upon_error to not contain duplicate values in value_types. I chose to change the behavior of concat_type_lists_unique_t, but I'm happy to take another approach (such as directly changing upon_error and possibly other algos that might have a similar problem).
ccotter
commented
Jun 26, 2023
test/type_list_test.cpp
Outdated
| >); | ||
| static_assert(std::is_same_v< | ||
| unique_type_list_elements_t<type_list<int, double, int>>, | ||
| type_list<double, int> |
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Note that my hasty implementation of unique_type_list_elements_t does not preserve order, or rather, it removes duplicate items from the front rather than end of list.
ispeters
requested changes
Jun 26, 2023
Co-authored-by: Ian Petersen <[email protected]>
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The current behavior of concat_type_lists_unique_t is a little confusing.
In other words, concat_type_lists_unique_t is not commutative.
The docs seemed to indicate concat_type_lists_unique_t expected the lists to already contain unique elements (the comment seemed incomplete though). I am changing the behavior of concat_type_lists_unique_t to remove duplicate elements from the input lists, since it conveniently fixes any sender algos that use it to construct the value_types of the output sender to not contain duplicate types.