[Pythonmac-SIG] py2app and PyQt: QT plugins cause loading multiple QT library versions

Sun Nov 25 21:02:35 CET 2012

Hi Ronald,

maybe my way to reply to this thread was the wrong approach.
I thought I had found the reason why Michael had problems,
because I hit that, too.

But it was not a py2app question at all that I wanted to ask.

Instead I thought you are the current maintainer of macholib,
and I wanted to point you at a possible bug in there that is
hidden since a long time.

I will ask a specific question about what I found and contact
the author of macholib.

Is it you, or still Bob Ippolito?

Sorry for being confusing ;-)

Cheers - Chris

On 11/25/12 2:36 PM, Ronald Oussoren wrote:
> On 24 Nov, 2012, at 21:50, Christian Tismer <tismer at stackless.com> wrote:
>
>> Howdy,
>>
>> On 31.05.12 21:46, Michael McCracken wrote:
>>> New user, so new thread, in reference to "(PyQt and py2app) Gui starts
>>> in IDLE but not as app".
>>>
>>> This happens when Qt loads image plugins from the
>>> system location (likely set during Qt's configure), which
>>> then load the system Qt.
>>>
>>> The problem and a workaround are described here:
>>> http://lists.trolltech.com/qt-interest/2008-09/thread00258-0.html
>>>
>>> py2app's PyQt sample doesn't exercise enough of Qt to hit this problem.
>>> I'm not sure exactly what part of Qt you'd need to trigger it, but
>>> I guess the Color Picker might work.
>>>
>>> The quick way, if you know you don't need these plugins, is to
>>> create an empty qt.conf file at MyApp.app/Contents/Resources/qt.conf.
>>>
>> ...
>>
>> I've hit a similar problem when trying to build a stand-alone pyside.
>> Starting with a modified setup.py (not yet ready), I created a working
>> pyside for virtualenv.
>> The missing part was support for 'setup.py --standalone', so I found
>> macholib which does a great job in creating the missing bits.
> I don't quite understand, does "python setup.py py2app" not work with pyside in a virtualenv?
>
> If so: did you have to do anything special to build such a pyside?
>
>> I simply used a few lines of Python to try out if macholib works for me,
>> like so:
>>
>>> from macholib.MachOStandalone import MachOStandalone
>>> from macholib.util import strip_files
>>> path='/Users/tismer/src/daniel/pydica/lib/python2.7/site-packages/PySide'
>>> files = MachOStandalone(path).run(contents='@rpath/Contents')
> You can also use "python -m macholib standalone" with recent releases
> of macholib.
>
>> This works great so far, but the generated pyside complains about duplicate libraries.
>> When I uninstall Qt, it does not find its image plugins.
>>
>> I guess there is a bug somewhere, which causes the following observation:
> This looks like a problem that is hopefully fixed for PyQt: Qt probably uses the
> wrong prefix to find its addons (the virtualenv location instead of the application bundle),
> and that causes it to load an image plugin from the virtualenv which again pulls
> in libQt from the virtualenv and then you end up with duplicate symbols and later
> on a crash.
>
> For PyQt this was fixed by loading a qt.conf into the application bundle, I added
> simular code for pyside, but that obviously didn't work.
>
>> $ otool -L /usr/local/Cellar/qt/4.8.3/plugins/imageformats/libqtiff.dylib
>> /usr/local/Cellar/qt/4.8.3/plugins/imageformats/libqtiff.dylib:
>>     libqtiff.dylib (compatibility version 0.0.0, current version 0.0.0)
>> /usr/local/Cellar/qt/4.8.3/lib/QtGui.framework/Versions/4/QtGui (compatibility version 4.8.0, current version 4.8.3)
>> /usr/local/Cellar/qt/4.8.3/lib/QtCore.framework/Versions/4/QtCore (compatibility version 4.8.0, current version 4.8.3)
>>     /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.5)
>>     /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 56.0.0)
>>     /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 169.3.0)
>>     /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1669.0.0)
>>
>> $ otool -L /Users/tismer/src/daniel/pydica/lib/python2.7/site-packages/PySide/plugins/imageformats/libqtiff.dylib
>> /Users/tismer/src/daniel/pydica/lib/python2.7/site-packages/PySide/plugins/imageformats/libqtiff.dylib:
>>     @rpath/Contents/mageformats/libqtiff.dylib (compatibility version 0.0.0, current version 0.0.0)
>> @rpath/Contents/Frameworks/QtGui.framework/Versions/4/QtGui (compatibility version 4.8.0, current version 4.8.3)
>> @rpath/Contents/Frameworks/QtCore.framework/Versions/4/QtCore (compatibility version 4.8.0, current version 4.8.3)
>>     /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.5)
>>     /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 56.0.0)
>>     /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 169.3.0)
>>     /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1669.0.0)
>>
>> The problem might be this line:
>> @rpath/Contents/mageformats/libqtiff.dylib
>>
>> The "i" from "imageformats" is missing!
>>
>> This _might_ be related to the unusual case that "libqtiff" has no path at all, or something else
>> is funny, and we end up with a name that will not be found at all.
>> Then the loader finds the plugin in the installed Qt, which causes it to load everything
>> again from there.
>>
>> Is that a possible explaining?
>> I just found that and had not the time to debug it thoroughly.
> Did you use the most recent release of py2app?
>
> If so, there is pyside support code in py2app/recipes/pyside.py and support code
> for PyQt in py2app/recipes/sip.py.  The latter works with PyQt on my machine,
> although with a system-wide install not an installation in a virtualenv.
>
> Ronald
>

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