Optional Functions

Collaboration diagram for Optional Functions:

Macros
#define	APR_OPTIONAL_FN_TYPE(name)   apr_OFN_##name##_t
#define	APR_DECLARE_OPTIONAL_FN(ret, name, args)   typedef ret (APR_OPTIONAL_FN_TYPE(name)) args
#define	APR_REGISTER_OPTIONAL_FN(name)
#define	APR_RETRIEVE_OPTIONAL_FN(name)    (APR_OPTIONAL_FN_TYPE(name) *)apr_dynamic_fn_retrieve(#name)

Typedefs
typedef void()	apr_opt_fn_t(void)

Functions
void	apr_dynamic_fn_register (const char *szName, apr_opt_fn_t *pfn)
apr_opt_fn_t *	apr_dynamic_fn_retrieve (const char *szName)

Detailed Description

Typesafe registration and retrieval of functions that may not be present (i.e. functions exported by optional modules)

Macro Definition Documentation

APR_DECLARE_OPTIONAL_FN

#define APR_DECLARE_OPTIONAL_FN	(		ret,
			name,
			args
	)		typedef ret (APR_OPTIONAL_FN_TYPE(name)) args

Declare an optional function.

Parameters

ret	The return type of the function
name	The name of the function
args	The function arguments (including brackets)

APR_OPTIONAL_FN_TYPE

#define APR_OPTIONAL_FN_TYPE

(

name

)

apr_OFN_##name##_t

The type of an optional function.

Parameters

name	The name of the function

APR_REGISTER_OPTIONAL_FN

#define APR_REGISTER_OPTIONAL_FN

(

name

)

Value:

  do { \
  APR_OPTIONAL_FN_TYPE(name) *apu__opt = name; \
  apr_dynamic_fn_register(#name,(apr_opt_fn_t *)apu__opt); \
} while (0)

Register an optional function. This can be later retrieved, type-safely, by name. Like all global functions, the name must be unique. Note that, confusingly but correctly, the function itself can be static!

Parameters

name	The name of the function

APR_RETRIEVE_OPTIONAL_FN

#define APR_RETRIEVE_OPTIONAL_FN

(

name

)

(APR_OPTIONAL_FN_TYPE(name) *)apr_dynamic_fn_retrieve(#name)

Retrieve an optional function. Returns NULL if the function is not present.

Parameters

name	The name of the function

Typedef Documentation

apr_opt_fn_t

typedef void() apr_opt_fn_t(void)

XXX: This doesn't belong here, then! Private function! DO NOT USE!

Function Documentation

apr_dynamic_fn_register()

void apr_dynamic_fn_register	(	const char *	szName,
		apr_opt_fn_t *	pfn
	)

apr_dynamic_fn_retrieve()

apr_opt_fn_t* apr_dynamic_fn_retrieve

(

const char *

szName

)

Private function! DO NOT USE!