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...-优快云博客

作者发现并报告了Lua标准库中set模块的一个小bug，该bug导致两个集合判断相等时出现错误。通过邮件交流，作者不仅成功地帮助项目修复了这个bug，还促使了其他相关改进。

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：

  --@funcpropersubset:Findwhetheroneset is apropersubsetof 
 --another 
 --@params,t:sets 
 --@returns 
 --@paramr:true if s is apropersubsetoft,falseotherwise 
 functionpropersubset(s,t) 
  return subset(s,t) and  not subset(t,s) 
 end 
 
 --@funcequal:Findwhethertwosetsareequal 
 --@params,t:sets 
 --@returns 
 --@paramr:true if setsareequal,falseotherwise 
 functionequal(s,t)  
  return subset(s,t) and subset(s,t)  
 end 
 
 --@headMetamethods for sets 
 --set+table=union 
 metatable.__add=union 
 --set-table=setdifference 
 metatable.__sub=difference 
 --set/table=intersection  
 metatable.__div=intersection  
 --set<=table=subset 
 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：）

  --@funcintersection:Findtheintersectionoftwosets 
 --@params,t:sets 
 --@returns 
 --@paramr:setintersectionofs and t 
 functionintersection(s,t) 
 localr=new{} 
  for e in elements(s)do 
  if member(t,e)then 
 insert(r,e) 
 end 
 end 
  return r 
 end 
 
 --@funcunion:Findtheunionoftwosets 
 --@params,t:sets 
 --@returns 
 --@paramr:setunionofs and t 
 functionunion(s,t) 
 localr=new{} 
  for e in elements(s)do 
 insert(r,e) 
 end 
  for e in elements(t)do 
 insert(r,e) 
 end 
  return r 
 end 
 
 --@funcsubset:Findwhetheroneset is asubsetofanother 
 --@params,t:sets 
 --@returns 
 --@paramr:true if s is asubsetoft,falseotherwise 
 functionsubset(s,t) 
  for e in elements(s)do 
  if  not member(t,e)then 
  return false 
 end 
 end 
  return true 
 end 
 
 --@funcpropersubset:Findwhetheroneset is apropersubsetof 
 --another 
 --@params,t:sets 
 --@returns 
 --@paramr:true if s is apropersubsetoft,falseotherwise 
 functionpropersubset(s,t) 
  return subset(s,t) and  not subset(t,s) 
 end 
 
 --@funcequal:Findwhethertwosetsareequal 
 --@params,t:sets 
 --@returns 
 --@paramr:true if setsareequal,falseotherwise 
 functionequal(s,t)  
    return subset(s,t) and subset(t,s)  
 end 
 
 --@headMetamethods for sets 
 --set+table=union 
 metatable.__add=union 
 --set-table=setdifference 
 metatable.__sub=difference 
 --set*table=intersection  
 metatable.__mul=intersection  
 --set/table=symmetricdifference 
 metatable.__div=symmetric_difference 
 --set<=table=subset 
 metatable.__le=subset 
 --set<table=propersubset 
 metatable.__lt=propersubset 