Fixing 'Cannot Define Public Member Inside Private Type' in Ada

Ada’s strong emphasis on encapsulation often causes confusion with errors like Cannot Define Public Member Inside Private Type. This occurs when you try to declare public operations or attributes for a type marked as private.

To resolve this, understand the distinction between private and limited private types in Ada.

A private type hides implementation details but allows forward declarations, while a limited private type prevents assignment operations outright.

If you’re encountering this error, it’s likely due to an incorrect placement of the public operation definition.

Ensure that public members for a private type are declared in the package specification, not the body.

For instance, if type T is private; is declared in the spec, any associated public procedure like procedure Do_Something (X : T); must also be defined in the spec.

Place implementation details in the body.

Alternatively, if encapsulation isn’t required, switch the type to a record or remove the private specifier.

Use pragma Inline judiciously to optimize frequently used public members.

By addressing this error, you ensure that your Ada code adheres to the language’s design philosophy of clear and intentional encapsulation.