'lightweight' QDir::isAbsolutePath replacement ?

Thiago Macieira thiago at kde.org
Tue Mar 11 13:01:47 GMT 2008

On Monday 10 March 2008 20:20:42 Ralf Habacker wrote:
> Thiago Macieira schrieb:
> > Ralf Habacker wrote:
> >> But - now the main question - is anyone from the trolltech devs here who
> >> can ensure that such a patch would be accepted ?
> >
> > Yes.
> >
> > Everybody laughed at lunch when I explained the number of classes it had
> > to go through just to do some string comparisons (on Unix, to look at the
> > first character).
> >
> > Depending on the size of the patch, I'll push it to Qt 4.4.
> The patch is appended. It adds
> static bool QFileInfo::isAbsolute(const QString &path);
> static bool QFileInfo::isRelative(const QString &path);
> and fixes
> static bool QDir::isAbsolutePath(const QString &path);
> static bool QDir::isRelativePath(const QString &path);
> all the above mentioned methods are based on
> static bool QFSFileEngine:isAbsolutePath(const QString &path);
> static bool QFSFileEngine::isRelative(const QString &path);
> which makes the internal string compare functions accesable

I have looked at the patch and it looks sane. At least, it didn't break any 
existing tests we have.

HOWEVER, it introduces a possibly bad behaviour change: if you have:
using a dedicated file engine, only that file engine is capable of knowing 
whether the given filename is an absolute path or not. Note how there are no 
slashes in the given filename (it's *not* a URL), but it still could be 
considered an absolute path.

So I don't think we can escape the creation of a file engine. The best I can 
do is go through the attempts to create, but in case of fallback to the 
default file engine, not create it.

I'll work on this a little more.

  Thiago Macieira  -  thiago (AT) macieira.info - thiago (AT) kde.org
    PGP/GPG: 0x6EF45358; fingerprint:
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