[PyKDE] strange seg fault with SIGNAL('PyObject *')

Patrick Stinson patrickkidd at gmail.com
Thu Mar 23 03:47:30 GMT 2006

I don't have debuggin symbols installed, but I am consistently getting a seg
fault after calling the python slot connected to SIGNAL('PyObject *') from a
QWidget subclass. I am usually passing a python string with the signal, but
if I pass None instead, it doesn't crash. I have a button group emitting
clicked(QAbstractButton *), which emits this signal.

the connecting code is as follows (sorry for the length), good luck:

import os
from PyQt4.QtCore import QObject, SIGNAL
from PyQt4.QtGui import QPushButton, QApplication, QWidget, QHBoxLayout
from PyQt4.QtGui import QButtonGroup, QPalette, QColor

# ~/.pksampler
PATCH_DIR = os.path.join(os.environ['HOME'], '.pksampler')
LAYERS = ['bass', 'drums', 'lead', 'misc', 'pads']

def find_patches():
    patches = [i for i in os.listdir(PATCH_DIR)
               if os.path.isdir(os.path.join(PATCH_DIR, i))]
    return patches

def extension(fpath):
    """ return the extension of fpath, not including the . """
    return fpath[fpath.rfind('.')+1:]

def can_open(fpath):
    exists = os.access(fpath, os.R_OK)
    supported = extension(fpath) in ('wav', 'aiff')
    return exists and supported

class PatchSelector(QWidget):
    def __init__(self, parent=None):
        QWidget.__init__(self, parent)
        Layout = QHBoxLayout(self)

        self.group = QButtonGroup(self)

        self.buttons = []
        for index, name in enumerate(find_patches()):
            button = QPushButton(name)

            palette = QPalette(button.palette())

            self.group.setId(button, index)

                        SIGNAL('buttonClicked(QAbstractButton *)'),

    def clicked(self, button):
        name = str(button.text())
        self.selected = name
        self.emit(SIGNAL('selected(PyObject *)'), name)

class Patch:

    name = None
    layers = None

    def __init__(self, name):
        self.name = name
        self.homedir = os.path.join(PATCH_DIR, name)
        self.layers = {}

        for layer in LAYERS:
            self.layers[layer] = []
            lpath = os.path.join(self.homedir, layer)

            if os.path.isdir(lpath):
                self.layers[layer] = []
                for fname in os.listdir(lpath):
                    print 'LPATH',lpath

               # THIS CRASHES IF I ENABLE THESE **************************8

                #    fpath = os.path.join(lpath, fname)
                #    print 'FPATH',fpath
                #    #if can_open(fpath):
                #    #    self.layers[layer].append(fpath)

if __name__ == '__main__':
    import sys
    def selected(name):
        print 'Selected:',name, Patch(name)
    a = QApplication(sys.argv)
    w = PatchSelector()
    QObject.connect(w, SIGNAL('selected(PyObject *)'), selected)
    #QObject.connect(w, SIGNAL('selected()'), selected)

Patrick Kidd Stinson
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