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XFN assumes the following model for attributes. A set of zero or more attributes is associated with a named object. Each attribute in the set has a unique attribute identifier, an attribute syntax,
and a (possibly empty) set of distinct data values. Each attribute value has an opaque data type. The attribute identifier serves as a name for the attribute. The attribute syntax indicates how the value
is encoded in the buffer.
The operations of the base attribute interface may be used to examine and modify the settings of attributes associated with existing named objects. These objects may be contexts or other types of
objects. The attribute operations do not create names or remove names from contexts.
The range of support for attribute operations may vary widely. Some naming systems may not support any attribute operations. Other naming systems may only support read operations, or operations on
attributes whose identifiers are in some fixed set. A naming system may limit attributes to have a single value, or may require at least one value. Some naming systems may only associate attributes with
context objects, while others may allow associating attributes with non-context objects.
These are the interfaces:
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#include <xfn/xfn.h>
FN_attribute_t *fn_attr_get(FN_ctx_t *ctx, const FN_composite_name_t *name,
const FN_identifier_t *attribute_id, FN_status_t *status);
int fn_attr_modify(FN_ctx_t *ctx, const FN_composite_name_t *name,
unsigned int mod_op, const FN_attribute_t *attr, FN_status_t *status);
FN_attrset_t *fn_attr_get_ids(FN_ctx_t *ctx, const FN_composite_name_t *name,
FN_status_t *status);
FN_valuelist_t *fn_attr_get_values(FN_ctx_t *ctx,
const FN_composite_name_t *name,
const FN_identifier_t *attribute_id, FN_status_t *status);
FN_attrvalue_t *fn_valuelist_next(FN_valuelist_t *vl,
FN_identifier_t **attr_syntax,
FN_status_t *status);
void fn_valuelist_destroy(FN_valuelist_t *vl, FN_status_t *status);
FN_multigetlist_t *fn_attr_multi_get(FN_ctx_t *ctx,
const FN_composite_name_t *name, const FN_attrset_t *attr_ids,
FN_status_t *status);
FN_attribute_t *fn_multigetlist_next(FN_multigetlist_t *ml,
FN_status_t *status);
void fn_multigetlist_destroy(FN_multigetlist_t *ml, FN_status_t *status);
int fn_attr_multi_modify(FN_ctx_t *ctx, const FN_composite_name_t *name,
const FN_attrmodlist_t *mods, FN_status_t *status,
FN_attrmodlist_t **unexecuted_mods);
FN_attrset_t *fn_ctx_get_syntax_attrs(FN_ctx_t *ctx,
const FN_composite_name_t *name, FN_status_t *status);
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The following describes briefly the operations in the base attribute interface. Detailed descriptions are given in the respective reference manual pages for these operations.
fn_attr_get() returns the attribute identified. fn_attr_modify() modifies the attribute identified as described by mod_op.
fn_attr_get_ids() returns the identifiers of the attributes of the named object.
fn_attr_get_values() and its set of related operations are used for returning the individual values of an attribute.
fn_attr_multi_get() and its set of related operations are used for returning the requested attributes associated with the named object. fn_attr_multi_modify()
modifies multiple attributes associated with the named object in a single invocation.
fn_ctx_get_syntax_attrs() returns the syntax attributes associated with the named context.
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