Re: share a stupid typo bug of me :(

[liam mail <liam.list@...>]

On 3 November 2012 16:39, Rena <hyperhacker@gmail.com> wrote:
> On 2012-11-03 5:21 AM, "Xavier Wang" <weasley.wx@gmail.com> wrote:
>>
>> Hi list,
>>
>> this morning I'm writing a Lua script converting UnicodeData.txt from
>> unicode.org to a C file, just like the one slnunicode used. I just
>> want to refactor slnunicode, make it simpler, smaller and fit Lua 5.2.
>>
>> After dig enough information from text database,  I use a variable
>> "line" to contain a line ready to write to C file, just like this:
>>
>> ----------------
>> local line = "    "
>> local lastv
>> for i, v in ipairs(pages) do
>>     --io.write("page["..i.."] = {"..table.concat(v, ", ").."}\n")
>>     if i == lastpage+1 then
>>         io.write(line:gsub(1, -3), "\n")
>>         line = "    ,"
>>         io.write "#if UTF_MAX > 3\n"
>>     end
>>     for _, v in ipairs(v) do
>>         line = line .. (v-1) .. ", "
>>         if #line > 70 then
>>             io.write(line:sub(1, -2), "\n")
>>             line = "    "
>>         end
>>     end
>>     lastv = v
>> end
>> io.write(line:sub(1, -3), "\n")
>> io.write [[
>> #endif /* UTF_MAX > 3 */
>> };
>> ]]
>>
>> -------------------
>>
>> just a part of script, did you see the issue in it? I don't. I just
>> find, all output data are correct, except the one above "#if UTF_MAX
>> >3" line -- some group index turned to negative number!!
>>
>> So I find in the algorithm to detect whether something I made it
>> wrong, but no luck, I tried every thing I have thought, but no lucky.
>> just the moment my computer get sucks, it run out all memory (4G) but
>> taskmgr.exe tell me no program use many memory.... sigh, so I guess
>> it's something wrong in Emergency garbage collector, so I close my
>> computer and going to sleep.
>>
>> After a enough sleep (waked up my be girlfriend's call), I'm trying
>> again to find out the issue. I boot my computer and everything the
>> same, so it can't the issue of garbage collector, so I copy code to a
>> fresh Lua script, and try to analyze it. it just output negative
>> number as the same. at last I try to write a small script only output
>> one line: it works! so it's the time to compare the two version of
>> snippet...
>>
>> OH MY GOD!!!!
>>
>> Yes, maybe you have found out the answer. there is nothing wrong with
>> my algorithm, nothing wrong with pretty print loop, the issue is just,
>> I need use "sub" on line, but not "*g*sub"!!
>>
>> God bless coders stay up all night T-T
>>
>> the lesson I have learned:
>> - Don't make simple thing complicate.
>> - go to bed and have a *good* sleep before you work.
>> - hi Roberto, when can we disable Auto Coercion? (Yes I know it's all
>> my bad, but make a Lua don't have auto coercion will make life easy)
>>
>> Thanks for everybody interesting my unfortunate accident :-) God bless
>> you!
>>
>> --
>> regards,
>> Xavier Wang.
>>
>
> It might be interesting to be able to turn off coercion temporarily by the
> debug library.
>
> As for silly bugs, I think my favorite was a script that insisted its input
> file was empty. I debugged it for about half an hour before realizing that
> it was telling the truth.
>
> Always make sure it's the program that's wrong, and not you... :)

Seeing as no one as of yet has brought it up.
I bet if you had test driven this then the mistake would either have
never been made or detected very quickly.

--Liam