[Interest] QTemporaryFile::open(OpenMode flags) is protected, but not in documentation

[Thiago Macieira]

On quarta-feira, 25 de setembro de 2013 23:04:42, Etienne Sandré-Chardonnal 
wrote:
> I do not want to read first, I want to write data, close, then reopen for
> reading (Used as a buffer for uploading large data over the network and
> avoid keeping it in memory).

Once you close the file, your data is gone. Your data only exists as long as 
you keep the file open.

Assuming well-behaved applications running on the system, you can open the file 
again in read-only mode, by using the same name. If you cannot assume well-
behaved applications (and defensive coding says you shouldn't), reopening the 
file by name is not guaranteed to get the same data. You must pass the already-
open file descriptor.

Now, you can tell QTemporaryFile to abandon the file: that is, set auto 
deletion to false and then destroy the object. But like I said above, the file 
might be deleted and recreated by another application before you can reopen it 
again.

In any case, every time you open a QTemporaryFile, you get a blank file. There 
is no data on the file, so it makes no sense to open it in read-only mode.

If you want to open a file with existing data, created by something else, use 
QFile, not QTemporaryFile.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center
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