.net - Why reference to a non-shared member of a Windows Form is allowed? -

we came across during problem determination within our code. we've fixed bug, question remains:

why reference non-shared member of "windows form" allowed?

in order replicate behaviour, create new windows forms application (i'm using vs2012, .net4.0), populate default form, form1.vb, with:

option strict on option explicit on  public class form1      private _private string      public readonly property notsharedproperty string                     return _private         end     end property  end class 

then add new class , call propertclass, fill with:

option strict on option explicit on  public class properclass      private _private string      public readonly property notsharedproperty string                     return _private         end     end property  end class 

then add class, call exampleclass , fill it:

option strict on option explicit on  public class exampleclass      public sub new()          if form1.notsharedproperty nothing             '.....................         end if          if properclass.notsharedproperty nothing             '.....................         end if       end sub  end class 

in exampleclass, properclass.notsharedproperty gives me "reference non-shared member requires object reference." 1 expect. form1.notsharedproperty not. why?

this 1 of many visual basic.net compatibility features.

when refer form type in old-school visual basic, reference default instance of form. that's how vb development done in past (and vb wasn't environment used convention). of time, had 1 instance of each form.

since you're not exploiting feature on purpose, never used default instance, , create own instances needed instead. in case, form1.notsharedproperty return whatever default is.