Access rights to a class property: special cases

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Access rights to a class property: special cases

The retrieval and assignment processes can be public, private or protected. The access rights of the property correspond to the less restrictive rights of the two processes.

Access rights of the property according to the access rights of the processes:


Assignment process / Retrieval process	Public	Protected	Private
Public	Public	Public	Public
Protected	Public	Protected	Protected
Private	Public	Protected	Private

The properties are accessible on the instances and by inheritance by respecting the standard restrictions of the public, protected and private inheritances.

If the access rights allow the read operations but not the write operations, the property is considered as being read-only.

If the access rights allow the write operations but not the read operations, the property is considered as being write-only.

These cases trigger an error during the compilation but no error is triggered at run time.

The tables below present the possible cases:

Using the class:
Assignment process
/
Retrieval process Public Protected Private
Public Read/Write Write-only Write-only
Protected Read-only Protected Protected
Private Read-only Protected Private

Using a derived class:
Assignment process
/
Retrieval process Public Protected Private
Public Read/Write Read/Write Write-only
Protected Read/Write Read/Write Write-only
Private Read-only Read-only Private

Using a class with public inheritance:
Assignment process
/
Retrieval process Public Protected Private
Public Read/Write Write-only Write-only
Protected Read-only Protected Protected
Private Read-only Protected Private

Using a class derived from a class with public inheritance:
Assignment process
/
Retrieval process Public Protected Private
Public Read/Write Read/Write Write-only
Protected Read/Write Read/Write Write-only
Private Read-only Read-only Private

Using a class with protected inheritance:


Assignment process / Retrieval process	Public	Protected	Private
Public	Protected inheritance	Protected inheritance	Protected inheritance
Protected	Protected inheritance	Protected inheritance	Protected inheritance
Private	Protected inheritance	Protected inheritance	Protected inheritance

Using a class derived from a class with protected inheritance:
Assignment process
/
Retrieval process Public Protected Private
Public Read/Write Read/Write Write-only
Protected Read/Write Read/Write Write-only
Private Read-only Read-only Private

Using a class with private inheritance:


Assignment process / Retrieval process	Public	Protected	Private
Public	Private inheritance	Private inheritance	Private inheritance
Protected	Private inheritance	Private inheritance	Private inheritance
Private	Private inheritance	Private inheritance	Private inheritance

Using a derived class with private inheritance:


Assignment process / Retrieval process	Public	Protected	Private
Public	Private inheritance	Private inheritance	Private inheritance
Protected	Private inheritance	Private inheritance	Private inheritance
Private	Private inheritance	Private inheritance	Private inheritance