6.14.2 Mathematical not–a–number error

The mathematical not–a–number exceptional–condition object–type has the purpose of describing an exceptional condition caused by a not–a–number result while computing a mathematical expression.

There should be only one mathematical not–a–number exceptional–condition object: the one predefined by CCExceptions and built into the library as statically allocated structure. Subtyping from this object–type is fine.

All the following definitions are accessible from the header file ccexceptions.h.

Struct Typedef: cce_descriptor_math_nan_t

Structure type representing the exceptional–condition object–type descriptor. This descriptor has the descriptor cce_descriptor_runtime_error_t as parent. It has the following public fields:

cce_descriptor_t descriptor

Core values of the exceptional–condition object–type descriptor.

Struct Typedef: cce_condition_math_nan_t

Structure type representing a mathematical not–a–number exceptional–condition object. It has the following public fields:

cce_condition_math_error_t math_error

Core values of the exceptional–condition object–type descriptor.

Function: cce_condition_t const * cce_condition_new_math_nan (void)

Return a pointer to the predefined, statically allocated, structure representing the exceptional–condition object of type cce_condition_math_nan_t.

Function: bool cce_condition_is_math_nan (cce_condition_t const * C)

Return true if the exceptional–condition object referenced by C is of type cce_condition_math_nan_t or it is derived from it; otherwise return false.

Facilities to derive an exceptional–condition object subtype

When deriving a subtype from cce_condition_math_nan_t we need the following functions.

Function: void cce_descriptor_set_parent_to(cce_descriptor_math_nan_t) (cce_descriptor_t * D)

Mutate the exceptional–condition object–type descriptor referenced by D so that its parent is the descriptor of cce_descriptor_math_nan_t. We should call this function in the initialisation module of the derived type.

Function: void cce_condition_init_math_nan (cce_condition_math_nan_t * C)

Initialise an already allocated exceptional–condition object. We should call this function from the initialisation function of the derived type.

Subtyping example

To define a subtype of cce_condition_math_nan_t we can copy the code in the files:

condition-subtyping-math-nan.c
condition-subtyping-math-nan-header.h
condition-subtyping-math-nan-body.c

under the tests directory of the source distribution; the code defines a new exceptional–condition object–type my_condition_math_nan_subtype_t.

This document describes version 0.9.0-devel.3 of CCExceptions.