What is the meaning of the planned "private protected" C# access modifier?

Here are all access modifiers in Venn diagrams, from more limiting to more promiscuous:

private:
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private protected: - added in C# 7.2
enter image description here

internal:
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protected:
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protected internal:
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public:
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According to "Professional C# 2008" by De Bill Evjen and Jay Glynn, page 1699:

private protected - "only derived types within the current assembly"

C++/CLI has a similar feature - Define and Consume Classes and Structs (C++/CLI) > Member visibility:

private protected -or- protected private - Member is protected inside the assembly but private outside the assembly.


This is just to provide a graph (made with http://ashitani.jp/gv/) of the different accessibility levels (images do not fit in comments).

digraph diagram of C# access levels

Each arrow means "is more restrictive than".

The CLR names are Private, FamilyANDAssembly, Assembly, Family, FamilyORAssembly, Public.

Much later edit: It turned out this nice new access level (with a really poor name) was not eventually included in C# 6.0. It is supported only from C# 7.2 (and I see you updated your question "tags").

Tags:

C#

Access Modifiers

C# 6.0

C# 7.2

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