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Re: Comment on File API's FileData::slice method

From: Arun Ranganathan <aranganathan@mozilla.com>
Date: Fri, 02 Oct 2009 09:15:25 -0700
Message-ID: <4AC6271D.7030807@mozilla.com>
To: Darin Fisher <darin@chromium.org>
CC: public-webapps@w3.org
Darin Fisher wrote:
> FileData::slice appears to be spec'd like so:
> FileData slice(in long long offset, in long long length); // throws
> FileException
> This suggests that it may throw a file exception.  I'm wondering if that is
> a requirement?  It seems that the rest of the methods are designed to report
> success or failure asynchronously.  I'm wondering why slice is not spec'd
> similarly.
> I think it would be bad for UAs to implement this exception since it would
> require a synchronous stat'ing of the filesystem.  That could hang the
> calling thread for a long time (consider network file systems).
> It seems like it would be better for the spec to encourage
> an asynchronous implementation.  For example, it should be the case that the
> FileData object returned by slice may or may not be valid.  The user would
> only find out when they try to use the FileData object.
By asynchronous, do you mean, with a callback function for the FileData 
object to be returned?  It sounds like what you are advocating is that 
this method does not raise an exception, but the FileData object is 
either valid or null.  If so, I think that sounds sensible.  Have I 
understood you correctly?

-- A*
Received on Friday, 2 October 2009 16:16:00 UTC

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