KTempFile->QTemporaryFile

[Jaison Lee]

One of the items in the kdelibs TODO is:

- KDE 4: Check if QTemporaryFile is good enough to dump KTempFile
  (Albert Astals Cid)

I've been looking at this recently along with Will Entriken.
QTemporaryFile is certainly capable of doing everything KTempFile does
and more, and it is probably worth the effort of making a few changes
to increase consistency between the APIs. There are a few caveats,
however:

* KTempFile defaults to ~/.kde/tmp-${HOSTNAME} whereas QTemporaryFile
defaults to /tmp (or /var/tmp)

* KTempFile does not autoremove by default whereas QTemporaryFile does.

* KTempFile HAS-A QFile whereas QTemporaryFile IS-A QFile, which just
makes some porting less simple than a search-and-replace.

* Most function calls have different names (KTempFile::setAutoDelete()
versus QTemporaryFile::setAutoRemove()) We should probably go with the
Qt vernacular for consistency.

* KTempFile is used EVERYWHERE in the codebase and in a variety of ways.

For all these reasons, I think we should create a new very small class
called KTemporaryFile that inherits from QTemporaryFile. It will be in
charge of setting the desired tmp directory, as well as setting
autoremove false (if we decide we want to keep that behaviour). It
will also provide a good place to put equivalents of the textStream()
and dataStream() functions which I think will be handy shortcuts and
make porting a bit easier.

My plan then would be:

Step 1) Create KTemporaryFile and mark KTempFile deprecated.
Step 2) Port all existing KTempFiles to KTemporaryFile.
Step 3) Remove KTempFile.

This will provide Will and I ample time to complete step 2, while
making sure that the codebase remains able to be compiled.

So how does this sound to everyone? Does this look like something
worth doing? Any comments on my overall plan? Should KTemporaryFile
still default autoRemove to false even though QTemporaryFile defaults
true? (Personally I would say no; take the Qt default in this case.)