diff options
| -rw-r--r-- | slv2/lv2.h | 25 |
1 files changed, 25 insertions, 0 deletions
@@ -260,6 +260,31 @@ typedef struct _LV2_Descriptor { * Hosts MUST NOT call cleanup() unless instantiate() was previously * called. */ void (*cleanup)(LV2_Handle Instance); + + /** Function pointer that can be used to return additional instance data for + * a plugin defined by some extenion (e.g. a struct containing additional + * function pointers). + * + * The actual type and meaning of the returned object MUST be specified + * precisely by the extension if it defines any extra data. If a particular + * extension does not define extra instance data, this function MUST return + * NULL for that extension's URI. If a plugin does not support any + * extensions that define extra instance data, this function pointer may be + * set to NULL rather than providing an empty function. + * + * The only parameter is the URI of the extension. The plugin MUST return + * NULL if it does not support the extension, but hosts SHOULD NOT use this + * as a discovery method (e.g. hosts should only call this function for + * extensions known to be supported by the plugin from the data file). + * + * NOTE: It is highly recommended that this function returns a struct, and + * NOT a direct function pointer. Standard C++ (for real reasons) does not + * allow type casts from void* to a function pointer type. To provide + * additional functions a struct should be returned containing the extra + * function pointers (which is valid standard C++, and a much better idea + * for extensibility anyway). + */ + void* (*extension_data)(const char * URI); } LV2_Descriptor; |