[PATCH 2 of 4] merge: use file context objects instead of acting directly on localrepo

[Sean Farley]

Pierre-Yves David writes:

> On 08/20/2014 12:56 PM, Sean Farley wrote:
>>
>> Pierre-Yves David writes:
>>
>>> So, reply to patch 1 failed to be sent so you got reply to patch 2
>>> without reply to patch one, lacking some useful context.
>>
>> Ah, yeah, that did help :-)
>>
>>> On 08/18/2014 11:08 PM, Sean Farley wrote:
>>>>
>>>> Pierre-Yves David writes:
>>>>
>>>>> On 08/18/2014 07:42 PM, Sean Farley wrote:
>>>>>> # HG changeset patch
>>>>>> # User Sean Farley <sean.michael.farley at gmail.com>
>>>>>> # Date 1406339242 18000
>>>>>> #      Fri Jul 25 20:47:22 2014 -0500
>>>>>> # Node ID d1a21cc0bc4ba5764a1f8760fd041a91939b4d00
>>>>>> # Parent  594d00e49cea6cd2ebb92c0570e7502f8797e232
>>>>>> merge: use file context objects instead of acting directly on localrepo
>>>>>
>>>>> Can you remind me what is the motivation behind have those methods
>>>>> (write/removes) on the filectx instead of the changectx itself?
>>>>
>>>> Merge (and friends) need a way to change the data for a filectx.
>>>> Currently, this is done by actually writing merged data onto disk, then
>>>> having localrepo.commit read that off of disk.
>>>
>>> Why does it especially needs to be from a filectx? Why can't it be from
>>> a changectx?
>>
>> Because filectxs hold the data of the file.
>>
>>>> If we want to do a merge in memory, then we need a way to change this
>>>> data in a filectx. That's why the previous patch needs to cache the
>>>> filectx in __getitem__ (so that the changed data is not thrown away).
>>>
>>> I know we need a was to store the data. but why can't this be done in
>>> changectx?
>>
>> Because filectxs hold the data of the file.
>
> Let me rephrase:
>
> Why do you insist for having the filectxs holding the data?
>
> The changectx could be holding the data too. What is the argument to get 
> put them on the filectxs ?

This is the way filectx and context is designed. It makes the most
sense. If you're going to put file data into contexts, then why not just
put it all into localrepo? You could also have a convenient way to
access it:

repo.getdata(ctx, filename)