真高兴啊。。。。实际的为开源事业做了点点贡献：），很久前指出的一个lua stdlib的bug得到确认

呵呵，是关于lua stdlib 库的set模块的bug，其实作者好像确认很久了。。。。但是我这段时间一直没有上gmail，所以没有看到。。。作者说，在新版中已经修改此bug...今天下了最新版，发现真是这样：）呵呵，真高兴啊，吸收了开源社区的那么多营养。。。总算有点报答了。。。当然，这仅仅是起步：）

实际流程贴一下。。。满足一下虚荣心。。。其实仅仅是一个很小的很容易发现的bug。。。呵呵，我当时学lua才一两周。。也不可能发现多么难的bug....lol

原来的lua stdlib set中某段程序如下：

1. --@funcpropersubset:Findwhetheroneset is apropersubsetof
2. --another
3. --@params,t:sets
4. --@returns
5. --@paramr:true if s is apropersubsetoft,falseotherwise
6. functionpropersubset(s,t)
7. return subset(s,t) and not subset(t,s)
8. end
10. --@funcequal:Findwhethertwosetsareequal
11. --@params,t:sets
12. --@returns
13. --@paramr:true if setsareequal,falseotherwise
14. functionequal(s,t)
15. return subset(s,t) and subset(s,t)
16. end
18. --@headMetamethods for sets
19. --set+table=union
20. metatable.__add=union
21. --set-table=setdifference
22. metatable.__sub=difference
23. --set/table=intersection
24. metatable.__div=intersection
25. --set<=table=subset
26. metatable.__le=subset

于是我发邮件给作者

hi all,
Thank you very much for your hard working with the LuaForWindows,I enjoy it so mush.
there is a bug to report as my return.
the set.lua file in the lualibs, 117th line.
source as this code:"return subset (s, t) and subset (s, t)"
it obviously should be "return subset (s,t) and subset(t, s)"
which means they are equal when s is the subset t and t is the subset s.
I hope I'm right and didn't disturb you.
BTW,there is a surprising attribute.
In the set's operations,div(/) mean intersection that is different from custom.
In the custom mul(*) denotes it,just like the <<programming in Lua>> writes in the 13th captial named "metatable and meatmethod"
Thank you for readingmy poor Chinglish. lol,I'mChinese.
Best wishes.
your honest
JTianLing from jtianling{at}gmail.com

luaforwindows的作者回信

Andrew Wilson to me, rrt, luaforwindows
show details Sep 3 Reply

Thanks for the bug report JTianLing, this particular module comes from
the stdlib library , I'll copy your report of this issue to the
administrator of that project http://luaforge.net/projects/stdlib/ .

Your English is great, you wouldn't want to even hear my Mandarin.
关心
Andrew Wilson

呵呵，不知道他这里说关心是什么意思......，惊奇的是。。。。他竟然还真能打中文字。。。。E文系统应该是没有中文输入法的吧。。。。

最后lua stdlib的作者回信：

Reuben Thomas to Andrew, me, luaforwindows
show details Sep 4 Reply

Thanks, this is quite correct. I've made a new release with this fix.

I see, I had actually forgotten that * is used in Modula-3 in the same way. I am happy to change this so that * is intersection and / is symmetric difference.

Thanks, I've made another release with these changes, and coincidentally fixed set.difference, which was also broken.

呵呵，最新版的set如下，可见已经修复，并且连那个我称为surprising attribute 的“/”符号表示交集也改了：）

1. --@funcintersection:Findtheintersectionoftwosets
2. --@params,t:sets
3. --@returns
4. --@paramr:setintersectionofs and t
5. functionintersection(s,t)
6. localr=new{}
7. for e in elements(s)do
8. if member(t,e)then
9. insert(r,e)
10. end
11. end
12. return r
13. end
15. --@funcunion:Findtheunionoftwosets
16. --@params,t:sets
17. --@returns
18. --@paramr:setunionofs and t
19. functionunion(s,t)
20. localr=new{}
21. for e in elements(s)do
22. insert(r,e)
23. end
24. for e in elements(t)do
25. insert(r,e)
26. end
27. return r
28. end
30. --@funcsubset:Findwhetheroneset is asubsetofanother
31. --@params,t:sets
32. --@returns
33. --@paramr:true if s is asubsetoft,falseotherwise
34. functionsubset(s,t)
35. for e in elements(s)do
36. if not member(t,e)then
37. return false
38. end
39. end
40. return true
41. end
43. --@funcpropersubset:Findwhetheroneset is apropersubsetof
44. --another
45. --@params,t:sets
46. --@returns
47. --@paramr:true if s is apropersubsetoft,falseotherwise
48. functionpropersubset(s,t)
49. return subset(s,t) and not subset(t,s)
50. end
52. --@funcequal:Findwhethertwosetsareequal
53. --@params,t:sets
54. --@returns
55. --@paramr:true if setsareequal,falseotherwise
56. functionequal(s,t)
57. return subset(s,t) and subset(t,s)
58. end
60. --@headMetamethods for sets
61. --set+table=union
62. metatable.__add=union
63. --set-table=setdifference
64. metatable.__sub=difference
65. --set*table=intersection
66. metatable.__mul=intersection
67. --set/table=symmetricdifference
68. metatable.__div=symmetric_difference
69. --set<=table=subset
70. metatable.__le=subset
71. --set<table=propersubset
72. metatable.__lt=propersubset

这虽然是一件芝麻一样的小事，但却是我个人第一次真正的为开源社区做贡献。。。。虽然仅仅是以bug report的形式：）立此存照：）