upd_data

Tell the ndarray that the scalar get_dataref returned was changed.

$pdl->upd_data; # after writing into the scalar $pdl->upd_data(1); # after replacing the scalar’s buffer

Any views derived from $pdl are told their parent changed, so they see the new data. For a small ndarray, whose scalar is a copy, the bytes are copied back and the scalar is released; a true argument keeps the scalar and makes it the ndarray’s data instead.

For an ndarray whose data is the scalar, the ndarray is pointed at the scalar’s buffer again - which is what makes a buffer that moved, such as one a file was mapped into, take effect.

Croaks with Trying to touch dataref of magical (mmaped?) pdl for an ndarray whose data is owned elsewhere, and with Trying to upd_data but datasv now length N instead of M if a small ndarray’s scalar was resized.