[Development] Qt 4.8.6 Release Plans

[Calogero Mauceri]

On 10/30/2013 8:59 AM, Konrad Rosenbaum wrote:
>
> Hi,
>
> On Wednesday 30 October 2013 00:58:05 Calogero Mauceri wrote:
>
> > The Qt documentation states that QDir::currentPath() returns "The
>
> > application working directory". Shouldn't the workind directory be
>
> > initialized with the path the application was launched from? If that's
>
> > not the case, which is the right way to obtain the working directory?
>
> > (not the executable path as the QApplication::applicationDirPath() is
>
> > returning)
>
> The current working directory is the directory the application is 
> currently working in (I know, it sounds like a tautology). Or in other 
> words: if you open a file with a relative path name, the current 
> working dir is the one in which your program looks for the file:
>
> QFile file("myfile");
>
> file.open(QIODevice::ReadOnly);
>
> is equivalent to:
>
> QFile file(QDir::current()+"/myfile");
>
> file.open(QIODevice::ReadOnly);
>
> You can change it with QDir::setCurrent or the underlying OS function 
> chdir.
>
> At application startup the current working directory is the exact same 
> directory that the parent was in when it spawned your process (this is 
> somewhat simplified). This is the same behavior over all desktop OSes. 
> The parent application is free to chose: it can simply refuse to care 
> (result: your CWD is more or less random from your programs 
> perspective; this is why an app started from a KDE desktop is almost 
> always in $HOME, but sometimes somewhere else); it can assume you are 
> a command line tool and want to work in the same place the shell is in 
> (that's what happens if you start anything from a shell); it can try 
> to be "helpful" and switch to the directory the binary is in 
> (apparently what Mac used to do); or it can try to make things 
> consistent by switching to the root directory (apparently what 10.9 does).
>
> In short: relying on the CWD at startup is misguided for most GUI 
> apps. If you need to be in a specific directory: use some other 
> mechanism to find it and then switch there, do not rely on being 
> placed there by magic.
>
> Places you may want to be:
>
> * somewhere relative to your binary: use 
> QApplication::applicationDirPath()
>
> - I do this in apps that have complex trees of files with data needed at
>
> runtime, apps that work in their own little "universe"
>
> * in the users home directory: QDir::setCurrent(QDir::homePath())
>
> - desktop apps that interact with user files
>
> * in the exact same place you were started from: don't move
>
> - this is true for most command line tools (like qmake, moc, ...)
>
> * in the root directory
>
> - true for most server processes (daemons, middleware, ...)
>
> * in the temp dir: use QDir::setCurrent(QDir::tempPath())
>
> - e.g. simulations that create some throw-away data only
>
> * in some dir that was configured by the user: read the config then switch
>
> - true for other server-like processes (e.g. automation software, ...)
>
> The tricky question we're trying to coax out of you: does 
> QDir.current() really return an empty string "" or the root directory 
> "/"? The former may indicate a bug on Apple's part, the latter is a 
> perfectly valid place to be in.
>

Konrad, thanks for your exaustive explanation.
It is clearer to me now that I can not rely on QDir::currentPath() 
function for what I need.

QDir::currentPath() on Mac OS X 10.9 is returning the root path "/".

Thanks,
     Calogero

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