Statement and Attribute: Specifies limitations on the use of module entities.
The PROTECTED attribute can be specified in a type declaration statement or a PROTECTED statement, and takes one of the following forms:
Type Declaration Statement:
type, [att-ls, ] PROTECTED [, att-ls] :: entity[, entity] ...
Statement:
PROTECTED [::]entity[, entity] ...
type |
Is a data type specifier. |
att-ls |
Is an optional list of attribute specifiers. |
entity |
Is the name of an entity in a module. |
The PROTECTED attribute can only appear in the specification part of a module.
The PROTECTED attribute can only be specified for a named variable that is not in a common block.
A non-pointer object that has the PROTECTED attribute and is accessed by use association can not appear in a variable definition or as the target in a pointer assignment statement.
A pointer object that has the PROTECTED attribute and is accessed by use association must not appear as any of the following:
A pointer-object in a NULLIFY statement
A pointer-object in a pointer assignment statement
An object in an ALLOCATE or DEALLOCATE statement
An actual argument in a reference to a procedure if the associated dummy argument is a pointer with the INTENT(OUT) or INTENT(INOUT) attribute.
The following restrictions apply outside of the module in which the entity has been given the PROTECTED attribute:
A non-pointer entity may not be defined or redefined.
A pointer entity may not have its association status changed through the pointer.
The following example shows a type declaration statement specifying the PROTECTED attribute:
INTEGER, PROTECTED :: D, E
Consider the following example:
MODULE counter_mod
INTEGER, PROTECTED :: current = 0
CONTAINS
INTEGER FUNCTION next()
current = current + 1 ! current can be modified here
next = current
RETURN
END FUNCTION next
END MODULE counter_mod
PROGRAM test_counter
USE counter_mod
PRINT *, next( ) ! Prints 1
current = 42 ! Error: variable is protected
END PROGRAM test_counter