Function lv2_raw::coreutils::lv2_features_query [−] [src]

pub unsafe fn lv2_features_query(
    features: *const *const LV2Feature, 
    query: &[FeatureHelper]
) -> *const c_char

Query a features array.

This function allows getting several features in one call, and detect missing required features, with the same caveat of lv2_features_data().

The arguments should be a series of const char* uri, void** data, bool required, terminated by a NULL URI. The data pointers MUST be initialized to NULL. For example:

@code LV2_URID_Log* log = NULL; LV2_URID_Map* map = NULL; const char* missing = lv2_features_query( features, LV2_LOG__log, &log, false, LV2_URID__map, &map, true, NULL); @endcode

@return NULL on success, otherwise the URI of this missing feature.