Re: Error using lua-users wiki sample Dir Tree Iterator code
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- Subject: Re: Error using lua-users wiki sample Dir Tree Iterator code
- From: mchalkley@...
- Date: 2015年3月12日 15:24:51 -0400
Thursday, March 12, 2015, 2:39:00 PM, you wrote:
> On Thursday, March 12, 2015 01:37:10 PM mchalkley@mail.com wrote:
>> When trying to use the first version of the "Dir Tree Iterator" sample
>> code on the lua-user.org Wiki page[1], I get the error:
>>
>> attempt to call field '?' (a userdata value)
>>
>> for this line:
>> local entry = diriters[#diriters]()
>>
>> The second example, using coroutines, works fine.
>>
>> What's the issue with the first example?
>>
> I believe LFS changed the way the lfs.dir function works. When this was
> written it must have only returned a unique closure for each directory. Now it
> uses an iterator function with state in a userdata. If you want to stare the
> iterator in a table you need to wrap it in a closure.
>> local diriters = {lfs.dir(dir)}
> and
>> table.insert(diriters, lfs.dir(filename))
> Change to
> local diriters = {diriterator(lfs.dir(dir))}
> table.insert(diriters, diriterator(lfs.dir(filename)))
> And add this function
> local function diriterator(func, state)
> return function()
> return func(state)
> end
> end
> That will do for lfs.dir which doesn't use the counter variable. There's
> another wrapper that works with any iterator, but that's an exercise for the
> reader.
Awesome - that explains it (and it works, even, with a fix to one
little typo)...
Thanks!
Mark