[Xapian-tickets] [Xapian] #448: Allow usage of custom stemmers

[Xapian]

#448: Allow usage of custom stemmers
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 Reporter:  esizikov     |        Owner:  olly    
     Type:  enhancement  |       Status:  reopened
 Priority:  normal       |    Milestone:          
Component:  Library API  |      Version:  1.0.17  
 Severity:  normal       |   Resolution:          
 Keywords:               |    Blockedby:          
 Platform:  All          |     Blocking:          
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Changes (by olly):

  * status:  closed => reopened
  * resolution:  duplicate =>
  * version:  => 1.0.17
  * component:  Other => Library API


Comment:

 OK, your initial description and the contents of the first two patches
 strongly suggested you were just trying to subclass Xapian::Stem in
 Python, which really won't work.  I don't think you need to enable
 directors for Xapian::Stem with your actual approach, and I also don't see
 why need to make Xapian::Stem's destructor virtual (since Xapian::Stem has
 no other virtual methods, and the destructor of your subclass doesn't do
 anything, I can't see why you need to do this).

 We can't make a change in 1.0.x which involves changing the library ABI
 incompatibly, and making Xapian::Stem's destructor virtual would be such a
 change, so if you do need to do that, this would have to be a trunk-only
 change.

 But if these alternative stemmers are useful, then I think it is better to
 build them in at the C++ API level - it's really an implementation detail
 whether they are part of Snowball or not, and that way they will
 automatically work from C++ and any wrapped language.

 Casting away const to write into the result of calling std::string::data()
 is undefined behaviour, so don't do that!

 Also, your claim of sole copyright on xapian_hunspell_stemmer.cpp is
 rather dubious since the definition of create_s() is lifted verbatim from
 Xapian's steminternal.cc (although it seems create_s() isn't actually used
 in your code).  We need to be particularly careful about tracking the
 copyright status of files in Xapian as we want to reach a point where we
 can relicense the code, but there are currently copyright holders who
 aren't interested in doing so.

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Ticket URL: <http://trac.xapian.org/ticket/448#comment:4>
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