[Xapian-devel] mutable Query objects

[Olly Betts]

On Thu, Feb 24, 2005 at 06:04:20PM +0000, Richard Boulton wrote:
> On Thu, 2005-02-24 at 16:54 +0000, Olly Betts wrote:
> > (a) implement a "deep copy" clone for Query objects and use it in
> > Enquire::set_query()
> > 
> > (b) make Query object immutable by replacing these non-const public
> > methods with extra constructor parameters:
> 
> I'd favour (b) too.  The query objects aren't usefully mutable, anyway
> (I can't think of a situation where it would be useful to take advantage
> of them being mutable), so it would be a waste of coding and testing
> time to implement a deep copy operation.

True, it seems to add complexity without a good reason.

> Also, it would mean that a
> deep copy had to be performed every time a query is set, which currently
> doesn't need to happen, so it will slow down the common case.

That's true.

Actually, there's a (c) - use copy-on-write to elide the deep copy in
the common case.  But that's also needless complication really.

OK, I'll implement (b).

Cheers,
    Olly