[Xapian-tickets] [Xapian] #593: [patch] Lua binding: check that module import is correct

[Xapian]

#593: [patch] Lua binding: check that module import is correct
-----------------------------------+----------------------------------------
 Reporter:  istr                   |       Owner:  olly    
     Type:  enhancement            |      Status:  assigned
 Priority:  normal                 |   Milestone:  1.3.1   
Component:  Xapian-bindings (Lua)  |     Version:  1.2.9   
 Severity:  normal                 |    Keywords:          
Blockedby:                         |    Platform:  All     
 Blocking:                         |  
-----------------------------------+----------------------------------------

Comment(by istr):

 Yes, sorry for the confusion. I did not realize a side effect in the swig
 binding of the -nomoduleglobal option in swig initially.

 In fact require in Lua 5.1 does both for the vast majority of modules
 available:[[BR]]
 - return the module as a table[[BR]]
 - register the module table within the current global environment[[BR]]

 If you want to use xapian in your own lua module, you need require to
 return the module table to be able to create a reference within the
 module's global environment.

 Cf.[[BR]]
 http://www.lua.org/manual/5.1/manual.html#2.9 (Environments)[[BR]]
 http://www.lua.org/manual/5.1/manual.html#pdf-require (Require)[[BR]]

 The problem with the -nomoduleglobal option is, that some functionality of
 the swig binding expects to find the module in the current  global
 environment 'xapian' (a bug that is not easy to fix: you need to enhance
 the userdata and improve the encapsulation of the C/Lua "objects"). So it
 is best to check that {{{ require'xapian' }}} registers the module in the
 current global environment AND returns the module table.

 Life would be much easier here if swig used the modern luaL_register /
 luaI_openlib method (lauxlib.c since Lua 5.1) and would not use its own
 registry method meant to be backwards compatible with Lua 5.0.


 As for the licencse: the patch is public domain, you may use it at
 whatever license you want (GPLv2, GPLv3, MIT, whatever)

-- 
Ticket URL: <http://trac.xapian.org/ticket/593#comment:6>
Xapian <http://xapian.org/>
Xapian