i.8.5.3-visibility-accessibility-and-security.md

I.8.5.3 Visibility, accessibility, and security

To refer to a named entity in a scope, both the scope and the name in the scope shall be visible (see §I.8.5.3.1). Visibility is determined by the relationship between the entity that contains the reference (the referent) and the entity that contains the name being referenced. Consider the following pseudo-code:

class A
{ int32 IntInsideA;
}
class B inherits from A
{ method X(int32, int32)
  { IntInsideA := 15;
  }
} 

If we consider the reference to the field IntInsideA in class A:

• We call class B the referent because it has a method that refers to that field,

• We call IntInsideA in class A the referenced entity.

There are two fundamental questions that need to be answered in order to decide whether the referent is allowed to access the referenced entity. The first is whether the name of the referenced entity is visible to the referent. If it is visible, then there is a separate question of whether the referent is accessible (see §I.8.5.3.2).

Access to a member of a type is permitted only if all three of the following conditions are met:

1. The type is visible and, in the case of a nested type, accessible.

2. The member is accessible.

3. All relevant security demands (see §I.8.5.3.3) have been granted.

An instantiated generic type is visible from some assembly if and only if the generic type itself and each of its component parts (generic type definition and generic arguments) are visible. For example, if List is exported from assembly A (i.e., declared "public") and MyClass is defined in assembly B but not exported, then List<MyClass> is visible only from within assembly B.

Accessibility of members of instantiated generic types is independent of instantiation.

Access to a member C<T₁,…T_n>.m is therefore permitted if the following conditions are met:

• C<T₁,…T_n> is visible.

• Member m within generic type C (i.e., C.m) is accessible.

• Security permissions have been granted.