Can't you just make Document non final and add a property (name of
class) that the reader will call Class.forName().newInstance() when
it needs to create document. As long as subclasses has a no-arg ctor,
what is the problem?
Note, if you allow this kind of support, passing Document instances
via RMI/other methods can be MESSY - and can create serious
performance /class loading issues.
On Mar 19, 2008, at 5:07 PM, eks dev wrote:
IndexableField really shouldn't be a subclass of whatever class is
returned after a sarch is done ... the methods used for accessing
the
"stored" value of a returned document make as little sense in the
context of IndexableField as the setBoost/Reader/TokenStream
functions of
Document currently make when a search is executed.
when all is said and done: an IndexableField and a SearchResultField
shouldn't have anything in common except *maybe* that they both
have a
fieldName.
Actually I think they do share alot more than just name of the
field? Accessing the "stored" value of a document is exactly what
indexing needs to do when it indexes the document in the first
place? Ie, a "stored" document "looks alot like" the document at
indexing time that had been stored. And things like isTokenized,
isTermVectorStored, isStoreOffsetWithTermVector, isBinary are
actually preserved in the index and known to the reader, so it's
worth having these methods available at search time?
Another case where it makes sense to mix read/write
responsibilities is setting backing storage for SearchResultField,
or in other words, "Dear lucene Document/LazyField, here is my byte
[], and this is an offset into this array where I would like you to
store the content of the stored field when you read it from your
mighty Directory, and please let me know how many bytes you have
read...."
for something like this the, the same setter you need for
IndexableField can be used in SearchResultField... sure,
SearchresultField can be mutable, but then, is this not just
repeating IndexableField methods?
tough one, gut feelings are to have this separation, examples show
that one class would do the job (like Doug's initial design, if my
memory goes that far :)
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