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Re: FileSystem API - overwrite flag for copy/move?

From: イアンフェッティ <ifette@google.com>
Date: Thu, 9 Sep 2010 00:37:09 -0700
Message-ID: <AANLkTinpivkbPkBzEXK1_uM+7agKmwZ74aa7yDQemgZz@mail.gmail.com>
To: Kinuko Yasuda <kinuko@chromium.org>
Cc: Eric Uhrhane <ericu@google.com>, Web Applications Working Group WG <public-webapps@w3.org>
I think recursive copy/remove is a very valid use case. As for overwrite, is
a flag necessary? On most OSes you already get overwrite as the default
behaviour (at least from APIs, many interactive UAs such as Explorer on
windows will prompt), is there a compelling argument why it should be
different for a web api?

On Thu, Sep 9, 2010 at 12:22 AM, Kinuko Yasuda <kinuko@chromium.org> wrote:

> On Thu, Sep 9, 2010 at 12:12 AM, Kinuko Yasuda <kinuko@chromium.org>wrote:
>
>> On Tue, Sep 7, 2010 at 6:12 PM, Eric Uhrhane <ericu@google.com> wrote:
>>
>>> On Mon, Aug 30, 2010 at 9:27 PM, Kinuko Yasuda <kinuko@chromium.org>
>>> wrote:
>>> > Hi,
>>> > I have a question about Entry.moveTo/copyTo behavior defined in
>>> > the File API: Directories and System [1].
>>> > Currently the API doesn't specify how Entry.moveTo() and copyTo()
>>> should
>>> > behave
>>> > when a source entry is a file and there's *already* a file at the
>>> > destination path.
>>> > Should UAs overwrite the existing file at the destination path or not?
>>> > Or maybe we should add an 'overwrite' flag to indicate if the script
>>> wants
>>> > to overwrite an existing file or not?
>>>
>>> I'm open to a flag.  We're already up to 4 parameters to each of those
>>> methods, though...5 is a bit ungainly.  I'm concerned that we might
>>> find another flag to add at some point, and we'd then be up to 6.
>>> What about adding an flags object, as in getFile, to allow for
>>> expansion?
>>
>>
>> Adding a flag or flags object (suppose the other thread about Flags will
>> be settled) sounds good to me.
>>
>> Or I think it's also ok to explicitly disallow overwriting copy/move, i.e.
>> specify that 'it is an error to copy or move a file or directory if there's
>> already an entry'.  In this case it might be better to have another error
>> code like ENTRY_EXISTS_ERR so that the user script can act differently.
>>  (But in general having a handy option would make programming much easier in
>> async context where every operation requires one or two callbacks.)
>>
>> If we're going to add 'overwrite' flag, there'll be a few more things to
>> be made clear.
>> For example I wonder how the overwriting copy/move should behave when
>> there's already a **directory** at the destination path/name.
>>
>> Should the UA remove the existing directory and create a new entry at the
>> same path?
>> This sounds reasonable but it'll also provide a handy alternative way to
>> remove a directory recursively.
>>
>
> By the way how do you think about recursive remove?
> Is there a reason (or past discussion) not to have recursive option in
> remove?  (I mean, other than the fact that adding more and more options to
> every method doesn't look very clean.)
>
> I found that it's not very easy to remove a directory when there're
> children in it -- it requires multiple DirectoryReader.readEntries and
> Entry.remove in a nested way.
>
> Thanks,
>
> Or should the UA create a new entry *under* the directory?
>> This behavior doesn't sound like 'overwriting'.  The resulting path will
>> be like 'destParentPath/name/name' which doesn't sound quite consistent with
>> the spec either.
>>
>>
>> > Similarly I wondered if we'd want to have a 'recursive' flag for
>>> > moveTo/copyTo.
>>> > I think for directories we can simply assume that the user wants to
>>> > move/copy
>>> > them recursively, but it might be good to add some notion about that in
>>> the
>>> > spec.
>>>
>>> How about I add a note indicating that directory copies are always
>>> recursive?
>>> I don't think we need anything for move.
>>
>>
>> This sounds good to me.  Thanks!
>>
>>
>>
>>>  > Thanks,
>>> > [1] http://dev.w3.org/2009/dap/file-system/file-dir-sys.html
>>> >
>>>
>>
>>
>
Received on Thursday, 9 September 2010 07:37:41 GMT

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