StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

POSet the generic return type
primarykey
Id
14221201
data
AcceptedAnswerId
14221350
AnswerCount
2
ClosedDate
CommentCount
4
CommunityOwnedDate
CreationDate
2013-01-08T17:58:54.667
FavoriteCount
0
LastActivityDate
2013-01-08T18:32:19.687
LastEditDate
2013-01-08T18:21:54.137
LastEditorUserId
687208
OwnerUserId
687208
ParentId
0
PostTypeId
1
Score
0
ViewCount
191
LastEditorDisplayName
text
Body
I've a function that works well for me: <pre><code>template <typename __container, typename __callback = std::function < void (typename __container::value_type, typename __container::value_type)> > int reduce(__container &&container, __callback &&callback) { auto current = container.begin(); for (auto value : container) *current = callback(*current, value); return *current; }; int result = functional::reduce(vector, [](const int current, const int next) -> int { return current + next; }); std::cout << result; // 10 </code></pre> And now, I'm going to unify the one: <pre><code>template <typename __container, typename __callback = std::function < void (typename __container::value_type, typename __container::value_type)> > auto reduce(__container &&container, __callback &&callback) -> decltype(__container::value_type); </code></pre> However I am getting the following error: <pre><code>reduce.cpp:61:9: error: no matching function for call to 'reduce' int i = reduce(vector, [](const int current, const int next) -> int { ^~~~~~~~~~~~~~~~~~ reduce.hpp:69:7: note: candidate template ignored: substitution failure [with __container = std::__1::list<int, std::__1::allocator<int>> &, __callback = <lambda at nott.cpp:61:36>] auto reduce(__container &&container, __callback &&callback) -> decltype(__container::value_type) ^ 1 error generated. make: *** [build] Error 1 </code></pre> How can I set the generic return type? UPDATE: <pre><code>template <typename __container, typename __callback> auto reducef(const __container& input, __callback callback) -> decltype(callback(std::declval<typename __container::value_type>(), std::declval<typename __container::value_type>())) { decltype( callback( std::declval<typename __container::value_type>(), std::declval<typename __container::value_type>() ) ) result{}; return std::accumulate(input.begin(), input.end(), result, callback); }; </code></pre>
Tags
<c++><c++11>
Title
Set the generic return type
singulars
PostAcceptedAnswerId
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USAlexander Abashkin
UserOwnerUserId
1. USAlexander Abashkin
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
2. PO
 singulars
 PostTypePostTypeId
 PTAnswer
VotesPostIdCreationDate
1. This table or related slice is empty.
CommentsPostId

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.