advanced search

We Recommend

CSS: The Definitive Guide CSS: The Definitive Guide
Provides you with a comprehensive guide to CSS implementation, along with a thorough review of all aspects of CSS 2.1. Updated to cover Internet Explorer 7, Microsoft's vastly improved browser, this new edition includes content on positioning, text wrapping (nowrap), lists and generated content, table layout, user interface, paged media, and more.

Posted By

kergoth on 12/18/06


Tagged

oop tables iteration map lua traversal deprecation functables metatables


Versions (?)


Lua: Sane Granular Defaults for User Supplied Data

Published in: Other 

Plain TextExpand 
  1. local mooDB
  2.  
  3. local defaults = {
  4.     a = {
  5.         foo = "bar"
  6.     },
  7.     b = 1,
  8.     c = {
  9.         bar = "foo"
  10.     },
  11. }
  12.  
  13. if not mooDB then
  14.     -- NOTE: This would not be in the actual real world code.  This
  15.     -- simulates user data, normally loaded from some sort
  16.     -- of datastore, which is SavedVariables in the case of
  17.     -- World of Warcraft.
  18.     mooDB = {
  19.         c = {
  20.             bop = "whee"
  21.         }
  22.     }
  23. end
  24.  
  25. function inheritdefaults(t, defaults)
  26.     for k,v in pairs(defaults) do
  27.         if t[k] then
  28.             if type(v) == "table" then
  29.                 inheritdefaults(t[k], v)
  30.             end
  31.         end
  32.     end
  33.  
  34.     local mt = getmetatable(t) or {}
  35.     function mt:__index(k)
  36.         return defaults[k]
  37.     end
  38.     return setmetatable(t, mt)
  39. end
  40.  
  41. inheritdefaults(mooDB, defaults)
  42.  
  43. assert(mooDB ~= defaults)
  44. assert(mooDB.a == defaults.a)
  45. assert(mooDB.c ~= defaults.c)
  46. assert(mooDB.a.foo == "bar")
  47. assert(mooDB.b == 1)
  48. assert(mooDB.c.bar == "foo")
  49. assert(mooDB.c.bop == "whee")

Report this snippet 

You need to login to post a comment.