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The blob access functions are similar to the atom accessing functions. Blobs being atoms, the atom functions operate on blobs and vice versa. For clarity and possible future compatibility issues, however, it is not advised to rely on this.
PL_BLOB_UNIQUEset, search the blob database for a blob of the same type with the same content. If found, unify t with the existing handle.
PL_BLOB_UNIQUEis not set, create a new blob handle. If
PL_BLOB_NOCOPYis set, associate it to the given memory; else, copy the memory to a new area owned by the blob. Call the acquire() function of the type.
It is possible that a blob referencing critial resources is created after which the unification fails. Typically these resources are eventually reclaimed because the new blob is not referenced and reclaimed by the atom garbage collector. As described with the release(f)unction, it can be desirable to reclaim the critical resources after the failing PL_unify_blob() call.
FALSE) or the blob is a reference to an existing blob (
TRUE). Reporting new/existing can be used to deal with external objects having their own reference counts. If the return is
TRUEthis reference count must be incremented, and it must be decremented on blob destruction callback. See also PL_put_atom_nchars().
TRUE. Otherwise return
FALSE. Each result pointer may be
NULL, in which case the requested information is ignored.
Get the data and type associated to a blob. This function is mainly
used from the callback functions described in section
188.8.131.52. Note that if the release() hook is called from PL_cleanup(),
blobs are releases regardless of whether or not they are referenced and
the order in which blobs are released is undefined (the order depends on
the ordering in the atom hash table). PL_blob_data()
may be called safely on a blob that has already been released. If this
happens during PL_cleanup()
the return value is guaranteed to be
NULL. During normal
execution it may return the content of a newly allocated blob that
reused the released handle.