vb.net - How to override properties in a derived class using generics -


i have following class setup , don't understand why won't compile.

i following error on "public overrides property f t"

  • 'public overrides property f t' cannot override 'public overridable property f x' because differ in return types.
  • this confuses me because constrained t derived x.

can explain how can accomplish goal? in end need have class , class b b inherits a. has overridable property f of type x, , b overrides f type derived x. suggestions appreciated. if cannot done, i'd interested know why (limitation of .net?) , how should go this.

public class x end class  public class y     inherits x end class  public class     public overridable property f x end class  public class a(of t x)     inherits     public overrides property f t end class  public class b     inherits a(of y)     public overrides property f y end class

thank-you!

new answer. don't think it's possible (exactly requested it), namely b overrides f type derived x, saw.

but hold y in private field in b , expose through f. you'd need cast f y access whatever functionality y provides on x. can done without changing a.

public class x     public overridable function z() string         return "x"     end function end class  public class y     inherits x     public overrides function z() string         return "y"     end function     public function foo() string         return "bar"     end function end class  public class     public overridable property f x end class  public class b     inherits     private _f y     public overrides property f x                     return _f         end         set(value x)             _f = directcast(value, x)         end set     end property end class

usage:

dim new a() dim x new x() dim b new b() dim y new y()  a.f = x console.writeline(a.f.z) ' console.writeline(directcast(a.f, y).foo()) ' invalidcastexception  b.f = y console.writeline(b.f.z) console.writeline(directcast(b.f, y).foo()) ' ok

output

x
y
bar


Comments

Post a Comment

Popular posts from this blog

Is there a better way to structure post methods in Class Based Views -

i'm using class based views in django , never specify url in ajax calls , omit action parameter in form because know these requests go through post method of class based view. notice view - profile page make many requests depending on user updating on page - post method become convoluted , if/else mess example: def post(self, request, *args, **kwargs): # handle user changing available date if request.post.get('availabledate') != none: self.updateavailabledate(request) return jsonresponse({'result':'success'}) if request.post.get('newprojectname') != none: creative_user = creativeuserprofile.objects.get(id = request.user.id) project = project.create_project(creative_user, request.post['newprojectname']) project.save() return jsonresponse({'projectid': project.id }) if request.post.get('projectimage') != none , request.files['file']: proj...
Read more

performance - Why is XCHG reg, reg a 3 micro-op instruction on modern Intel architectures? -

i'm doing micro-optimization on performance critical part of code , came across sequence of instructions (in at&t syntax): add %rax, %rbx mov %rdx, %rax mov %rbx, %rdx i thought had use case xchg allow me shave instruction , write: add %rbx, %rax xchg %rax, %rdx however, dimay found agner fog's instruction tables , xchg 3 micro-op instruction 2 cycle latency on sandy bridge, ivy bridge, broadwell, haswell , skylake. 3 whole micro-ops , 2 cycles of latency! 3 micro-ops throws off 4-1-1-1 cadence , 2 cycle latency makes worse original in best case since last 2 instructions in original might execute in parallel. now... cpu might breaking instruction micro-ops equivalent to: mov %rax, %tmp mov %rdx, %rax mov %tmp, %rdx where tmp anonymous internal register , suppose last 2 micro-ops run in parallel latency 2 cycles. given register renaming occurs on these micro-architectures, though, doesn't make sense me done way. why wouldn't register renamer ...
Read more

c# - Asp.net web api : redirect unauthorized requst to forbidden page -

im trying redirect unauthorized request forbidden page instead i'm getting forbidden page in response body , how can fix ? here's startup class : app.createperowincontext(storecontext.create); app.createperowincontext<applicationusermanager>(applicationusermanager.create); app.createperowincontext<applicationsigninmanager>(applicationsigninmanager.create); app.usecookieauthentication(new cookieauthenticationoptions { authenticationtype = defaultauthenticationtypes.applicationcookie, expiretimespan = timespan.fromdays(30), }); app.useexternalsignincookie(defaultauthenticationtypes.externalcookie); app.usetwofactorsignincookie(defaultauthenticationtypes.twofactorcookie, timespan.fromminutes(5)); app.usetwofactorrememberbrowsercookie(defaultauthenticationtypes.twofactorrememberbrowsercookie); the method im trying reach : [httpget] [authorize(roles = "admin")] public string getcurrentusername() { return userman...
Read more