Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Implicit interface implementation has a requirement that the generic constraints on the method declarations be equivalent, but not necessarily exactly the same in code. Additionally, generic type parameters have an implicit constraint of "where T : object". That is why specifying <code>C&lt;Object&gt;</code> compiles, it causes the constraint to become equivalent to the implicit constraint in the interface. (Section 13.4.3 of the <a href="http://www.microsoft.com/downloads/en/details.aspx?displaylang=en&amp;FamilyID=dfbf523c-f98c-4804-afbd-459e846b268e" rel="nofollow">C# Language Spec</a>).</p> <p>You're also correct that using an explicit interface implementation that calls into your constrained method will work. It provides a very clear mapping from the interface method to your implementation in the class where the constraints <em>cannot</em> differ, and then proceeds to call a similarly-named generic method (one that now has nothing to do with the interface). At that point, constraints on the secondary method can be resolved in the same way as any generic method call without any interface resolution issues.</p> <p>Moving the constraints from the class to the interface, in your second example, is better because the class will take its constraints from the interface by default. This also means that you must specify the constraints in your class implementation, if applicable (and in the case of Object it is not applicable). Passing <code>I&lt;string&gt;</code> means that you can't directly specify that constraint in code (because string is sealed) and so it must either be part of an explicit interface implementation or a generic type that will be equal to the constraints in both places.</p> <p>As far as I know, the runtime and the compiler use separate verification systems for constraints. The compiler allows this case but the runtime verifier doesn't like it. I want to stress that I don't know for sure why it has a problem with this, but I would guess that it doesn't like the potential in that class definition to <em>not</em> fulfill the interface constraints depending on what T ends up being set to. If anyone else has a definitive answer on this, that would be great.</p>
    singulars
    1. This table or related slice is empty.
    1. POWhy does this generics scenario cause a TypeLoadException?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USChris Hannon
    1. USChris Hannon
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThe use of string in my examples was a bad choice because it's sealed - thanks for pointing that out (fixed now). However in the end it makes no difference since I'm deliberately not matching the constraints, so nothing other than Object will compile. Helpful answer though, thank you. I looked at the part of the spec you referred to - hurts my head a bit.
      singulars
      1. PO
      1. USIgby Largeman
 

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.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload