5.11. Methods that Destroy the Instance Reference

If a method destroys the instance (that is, frees it) it can be marked with the DestroysInstance attribute. The method must return void. Although in most cases such a method would be bound as the free_function of the compact class.

If a function destroys an instance but provides a useable return value, instead, bind it as a static method which takes an owned variable for the instance:

typedef struct transaction Transaction;
Transaction begin_tx(Database *db);
void transaction_abort(Transaction *tx);
void transaction_commit(Transaction *tx);
bool transaction_try_commit(Transaction *tx);

[Compact]
[CCode (cname = "Transaction", free_function = "transaction_abort")]
public class Transaction {
    public Transaction (Database db);
    [DestroysInstance]
    public void commit ();
    public static bool try_commit (owned Transaction tx);
}