- From: Eric Uhrhane <ericu@google.com>
- Date: Thu, 16 Sep 2010 16:00:44 -0700
- To: Kinuko Yasuda <kinuko@chromium.org>
- Cc: ifette@google.com, Web Applications Working Group WG <public-webapps@w3.org>
2010/9/16 Kinuko Yasuda <kinuko@chromium.org>: > On Thu, Sep 16, 2010 at 2:50 PM, Eric Uhrhane <ericu@google.com> wrote: >> How about this? >> >> For a move/copy of a file on top of existing file, or a directory on >> top of an existing empty directory, you get an automatic overwrite. >> A move/copy of a file on top of an existing directory, or of a >> directory on top of an existing file, will always fail. >> A move/copy of a file or directory on top of an existing non-empty >> directory will always fail. > > This sounds good to me. > I think sticking to the compatibility with Posix would make sense to > developers too. > >> That matches Posix[1] rename behavior, and should cover most or all of >> the normal use cases. >> If necessary, we can consider adding a "don't overwrite" flag, but >> that may be difficult to implement without race conditions on all >> platforms. > > We can achieve this in a safer way by combining getFile/getDirectory > with exclusive flag and move/copy, so I think it's reasonable not to > have "don't overwrite" flag. > >> Regarding recursive deletion of directories: >> >> One option is to add a flag to remove(); that flag will be ignored if >> the Entry is a file, so it's not as clean as it might be, but it keeps >> the interface small. >> Another is to add a removeRecursively() method to DirectoryEntry; this >> makes it really clear what's going on, and might prevent some >> accidental deletions. > > I have no strong opinion on this but removeRecursively might be error prone? > (Recursive remove can be very destructive and it should be triggered > with an explicit intention.) Which do you think is more error-prone, a method called removeRecursively, or a boolean flag to remove? >> Which do you prefer? >> >> [1] http://www.opengroup.org/onlinepubs/009695399/functions/rename.html >> >> 2010/9/9 Kinuko Yasuda <kinuko@chromium.org>: >>> On Thu, Sep 9, 2010 at 12:37 AM, Ian Fette (イアンフェッティ) <ifette@google.com> >>> wrote: >>>> >>>> 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? >>> >>> Making overwriting mode default for copy/move sounds reasonable to me too. >>> Especially if we allow recursive remove (and I think there would be more >>> need for this one) it'd look more consistent. >>> As for providing options, I was a bit concerned about the complexity in >>> programming with nested callbacks, but in this case it's not a big deal >>> (we'll need only two) and wouldn't be a problem. >>> I'm more concerned with recursive remove though. The js code to do that >>> isn't very pretty. >>> >>>> 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, 16 September 2010 23:01:29 UTC