[MERGE] don't invoke os.rename on children with no contents

[Aaron Bentley]

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Robert Collins wrote:
> On Tue, 2007-06-05 at 21:10 -0400, Aaron Bentley wrote:
> 
> You're good to merge without doing the below.

Okay, have done so.

>> Now what you could do is this:
>>
>>      for trans_id in trans_ids:
>>          if trans_id not in self._new_contents:
>>              del self._limbo_files[trans_id]
>>              continue
>>          old_path = self._limbo_files[trans_id]
>>          new_path = self._limbo_name(trans_id, from_scratch=True)
>>          os.rename(old_path, new_path)
>>
>> Deleting the self._limbo_files entry forces it to be generated from
>> scratch on the next usage, rather than generating it from scratch now.
> 
> This is not related to merging - a more general api discussion:
> Interesting. Which is it that removes it from _limbo_files?

del self._limbo_files[trans_id]

I think we miscommunicated.

self._limbo_name(trans_id, from_scratch=True) has the side effect of
storing a new value in self._limbo_files[trans_id], overwriting any
existing value.

Either del self._limbo_files[trans_id] or self._limbo_name(trans_id,
from_scratch=True) ensures that self._limbo_files does not contain a
stale value.

> the
> _limbo_name call? It just appears hard to guess at whats happening..

Perhaps it would be clearer to scrag the from_scratch parameter, and do
this:

     for trans_id in trans_ids:
         old_path = self._limbo_files[trans_id]
         del self._limbo_files[trans_id]
         if trans_id in self._new_contents:
             new_path = self._limbo_name(trans_id)
             os.rename(old_path, new_path)

What do you think?

Aaron
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