StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

POVB typeof operator with generics
primarykey
Id
18245719
data
AcceptedAnswerId
0
AnswerCount
2
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2013-08-15T03:05:35.103
FavoriteCount
2
LastActivityDate
2017-05-22T23:24:51.533
LastEditDate
2013-08-15T03:08:39.047
LastEditorUserId
1366033
OwnerUserId
70716
ParentId
0
PostTypeId
1
Score
2
ViewCount
1058
LastEditorDisplayName
text
Body
When comparing types in VB the following works as expected and enables the current instance to be compared against a specific inherited class, in this case returning <code>False</code> (snippet from <a href="http://www.linqpad.net/" rel="nofollow">LINQPad</a>) <pre><code>Sub Main Dim a As New MyOtherChildClass a.IsType().Dump() End Sub ' Define other methods and classes here MustInherit class MyBaseClass Public Function IsType() As Boolean Return TypeOf Me Is MyChildClass End Function End Class Class MyChildClass Inherits MyBaseClass End Class Class MyOtherChildClass Inherits MyBaseClass End Class </code></pre> However when generics are introduced the VB compiler fails with the error <code>Expression of type 'UserQuery.MyBaseClass(Of T)' can never be of type 'UserQuery.MyChildClass'.</code> <pre><code>' Define other methods and classes here MustInherit class MyBaseClass(Of T) Public Function IsType() As Boolean Return TypeOf Me Is MyChildClass End Function End Class Class MyChildClass Inherits MyBaseClass(Of String) End Class Class MyOtherChildClass Inherits MyBaseClass(Of String) End Class </code></pre> The equivalent code in C# compiles and allows the comparison, returning the correct result <pre class="lang-cs prettyprint-override"><code>void Main() { var a = new MyOtherChildClass(); a.IsType().Dump(); } // Define other methods and classes here abstract class MyBaseClass<T> { public bool IsType() { return this is MyChildClass; } } class MyChildClass : MyBaseClass<string> { } class MyOtherChildClass : MyBaseClass<string> { } </code></pre> Why does the VB compiler not allow this comparison?
Tags
<vb.net><generics><typeof>
Title
VB typeof operator with generics
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USKyleMit
UserOwnerUserId
1. USbstoney
plurals
PostLinksPostIdRelatedPostId
1. PL
 singulars
 LinkTypeLinkTypeId
 LTLinked
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 POVB typeof operator with generics
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 POVB typeof operator with generics
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTApproveEditSuggestion
3. VO
 singulars
 PostPostId
 POVB typeof operator with generics
 UserUserId
 USKyleMit
 VoteTypeVoteTypeId
 VTFavorite
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.