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6.14.2.3 struct x1f4_a1screen_type

typedef struct x1f4_a1screen_type {
    int (*back)(void *, const struct x1f4_function_type *),
	(*fast)(void *, const struct x1f4_function_type *),
	(*lose)(void *, const struct x1f4_function_type *);
    void *data;
} x1f4_a1screen_type;

The struct x1f4_a1screen_type record describes function call observers.

See Call Observers.

back

The back field indicates the roll back method. It may be called when some other function call observer enter method has failed execution. It is passed the observing context (the data field in this very record) and possibly a struct x1f4_function_type description of the observed function as arguments, in this order. Return value is discarded.

data

The data field indicates the function call observing context. It is passed as the first argument to the function call observing methods and not interpreted otherwise.

fast

The fast field indicates the function call enter observing method. It is called before executing any observed function instruction and after the function arguments have been evaluated. It is passed the observing context (the data field in this very record) and possibly a struct x1f4_function_type description of the observed function as arguments, in this order. The method is expected to return zero for successful operation, non zero otherwise. For non zero return the program execution is terminated.

lose

The fast field indicates the function call completion observing method. It is called after the last observed function instruction has been executed. It is passed the observing context (the data field in this very record) and possibly a struct x1f4_function_type description of the observed function as arguments, in this order. The method is expected to return zero for successful operation, non zero otherwise. For non zero return the program execution is terminated.

See struct x1f4_function_type.