StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
6686491
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2011-07-13T22:32:45.653
FavoriteCount
0
LastActivityDate
2011-07-13T22:32:45.653
LastEditDate
2017-05-23T11:58:44.283
LastEditorUserId
-1
OwnerUserId
65299
ParentId
4373070
PostTypeId
2
Score
4
ViewCount
0
LastEditorDisplayName
text
Body
This answer describes another approach that results in more-readable, self-documenting client code. Motivation The <a href="https://stackoverflow.com/questions/4373070/how-do-i-get-an-instance-of-the-type-class-associated-with-a-context-bound/4373153#4373153"><code>context</code> method that I described previously</a> is a very general solution that works with any type class, without any additional effort. However, it may be undesirable for two reasons: <ul> <li>The <code>context</code> method cannot be used when the type parameter has multiple context bounds, since the compiler has no way to determine which context bound is intended.</li> <li>The reference to the generic <code>context</code> method harms readability of the client code.</li> </ul> Type-class-specific methods Using a method that is tied to the desired type class makes client code much more readable. This is the approach used in the standard library for the Manifest type class: <pre><code>// definition in Predef def manifest[T](implicit m: Manifest[T]) = m // example usage def getErasure[T: Manifest](x: T) = manifest[T].erasure </code></pre> Generalizing this approach The main drawback of using type-class-specific methods is that an additional method must be defined for every type class. We can ease this process with the following definitions: <pre><code>class Implicitly[TC[_]] { def apply[T]()(implicit e: TC[T]) = e } object Implicitly { def apply[TC[_]] = new Implicitly[TC] } </code></pre> Then a new type-class-specific implicitly-style method can be defined, for any type class: <pre><code>def numeric = Implicitly[Numeric] // or val numeric = Implicitly[Numeric] </code></pre> Finally, client code can use the Implicitly as follows: <pre><code>def add[T: Numeric](x: T, y: T) = numeric[T].plus(x, y) </code></pre>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POHow do I get an instance of the type class associated with a context bound?
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USCommunity
UserOwnerUserId
1. USAaron Novstrup
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. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

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.