What is the difference between protected and protected internal

Question

Can someone please explain the difference between the protected and protected internal modifiers in C   It looks like their behavior is identical

User · Answer

Think about protected internal as applying two access modifier  protected  and internal  on the same field  property or method  In the real world  imagine we are issuing privilege for people to visit museum    Everyone inside the city are allowed to visit museum  internal   Everyone outside of the city that their parents live here are allowed to visit museum  protected     And we can put them together in these way   Everyone inside the city  internal  and everyone outside of city that their parents live here  protected  are allowed to visit the museum  protected internal    Programming world  internal  The field is available everywhere in the assembly  project   It is like saying it is public in its project scope  but can not being accessed outside of project scope even by those classes outside of assembly which inherit from that class   Every instance of that type can see it in that assembly  project scope   protected  simply means that all derived classes can see it  inside or outside of assembly   For example derived classes can see the field or method inside its methods and constructors using  base NameOfProtectedInternal  So  putting these two access modifier together  protected internal   you have something that can being public inside the project  and can be seen by those which have inherited from that class inside their scope   They can be written in the internal protected  and does not change the meaning  but it is convenient to write it protected internal

User · Answer

The  protected internal  access modifier is a union of both the  protected  and  internal  modifiers   From MSDN  Access Modifiers  C  Programming Guide    protected      The type or member can be accessed only by code in the same class or   struct  or in a class that is derived from that class    internal      The type or member can be accessed by any code in the same assembly    but not from another assembly    protected internal      The type or member can be accessed by any code in the assembly in   which it is declared  OR from within a derived class in another   assembly  Access from another assembly must take place within a class   declaration that derives from the class in which the protected   internal element is declared  and it must take place through an   instance of the derived class type    Note that  protected internal means  protected OR internal   any class in the same assembly  or any derived class - even if it is in a different assembly       and for completeness   private      The type or member can be accessed only by code in the same class or   struct    public      The type or member can be accessed by any other code in the same   assembly or another assembly that references it    private protected      Access is limited to the containing class or types derived from the   containing class within the current assembly     Available since C  7 2

User · Answer

protected can be used by any subclasses from any assembly   protected internal is everything that protected is  plus also anything in the same assembly can access it   Importantly  it doesn t mean  subclasses in the same assembly  - it is the union of the two  not the intersection

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I have read out very clear definitions for these terms   Protected   Access is limited to within the class definition and any class that inherits from the class  The type or member can be accessed only by code in the same class or struct or in a class that is derived from that class   Internal   Access is limited to exclusively to classes defined within the current project assembly  The type or member can be accessed only by code in same class   Protected-Internal   Access is limited to current assembly or types derived from containing class

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public - The members  Functions  amp  Variables  declared as public can be accessed from anywhere   private - Private members cannot be accessed from outside the class  This is the default access specifier for a member  i e if you do not specify an access specifier for a member  variable or function   it will be  considered as private  Therefore  string PhoneNumber  is equivalent to private string PhoneNumber   protected - Protected members can be accessed only from the child classes   internal - It can be accessed only within the same assembly   protected internal - It can be accessed within the same assembly as well as in derived class

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There is still a lot of confusion in understanding the scope of  protected internal  accessors  though most have the definition defined correctly  This helped me to understand the confusion between  protected  and  protected internal    public is really public inside and outside the assembly  public internal   public external   protected is really protected inside and outside the assembly  protected internal   protected external   not allowed on top level classes   private is really private inside and outside the assembly  private internal   private external    not allowed on top level classes   internal is really public inside the assembly but excluded outside the assembly like private  public internal   excluded external   protected internal is really public inside the assembly but protected outside the assembly  public internal   protected external     not allowed on top level classes   As you can see protected internal is a very strange beast  Not intuitive   That now begs the question why didn t Microsoft create a  protected internal   excluded external   or I guess some kind of  private protected  or  internal protected   lol  Seems incomplete   Added to the confusion is the fact you can nest public or protected internal nested members inside protected  internal  or private types  Why would you access a nested  protected internal  inside an internal class that excludes outside assembly access   Microsoft says such nested types are limited by their parent type scope  but that s not what the compiler says  You can compiled protected internals inside internal classes which should limit scope to just the assembly   To me this feels like incomplete design  They should have simplified scope of all types to a system that clearly consider inheritance but also security and hierarchy of nested types  This would have made the sharing of objects extremely intuitive and granular rather than discovering accessibility of types and members based on an incomplete scoping system

User · Answer

This table shows the difference  protected internal is the same as protected  except it also allows access from other classes in the same assembly

User · Answer

Protected Member  Protected Member of a class in only available in the contained class  in which it has been declared  and in the derived class within the  assembly and also outside the assembly   Means if a class that resides outside the assembly can use the protected member of the other assembly by inherited that class only   We can exposed the Protected member outside the assembly by inherited that class and use it in the derived class only      Note  Protected members are not accessible using the object in the derived class    Internal Member  Internal Member of a class is available or access within the assembly either creating object or in a derived class or you can say it is  accessible across all the classes within the assembly      Note  Internal members not accessible outside the assembly either using object creating or in a derived class    Protected Internal  Protected Internal access modifier is combination Protected or Internal    Protected Internal Member can be available within the entire assembly in which it declared either creating object or by inherited that  class  And can be accessible outside the assembly in a derived class only      Note  Protected Internal member works as Internal within the same assembly and works as Protected for outside the assembly

User · Answer

Protected internal best suites when you want a member or type to be used in a derived class from another assembly at the same time just want to consume the member or type in the parent assembly without deriving from the class where it is declared  Also if you want only to use a member or type with out deriving from another class  in the same assembly you can use internal only

User · Answer

protected  the variable or method will be available only to child classes  in any assembly   protected internal  available to child classes in any assembly and to all the classes within the same assembly

User · Answer

In practice  about methods   protected - accessible for inherited classes  otherwise private   internal - public only for classes inside the assembly  otherwise private   protected internal - means protected or internal - methods become accessible for inherited classes and for any classes inside the assembly

[c#] What is the difference between 'protected' and 'protected internal'?

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